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RADIO FIELD INTENSITY MEASURLMEATS.

 

A Thesis submitted to the Faculty of

Michigan State College
of
Agriculture and Applied Science.

 

by

Robert D.Martin

Candidate for the Professional Degree
of Electrical Engineer;
1954.

 

 

THESS‘S

RADIO FIELD INTENSITY MEASUREMENTS.

Chapter One

THEORY OF RADIO WAVE PROPAGATION.

GENERAL THEORY:

 

A generalization of the theory of radio wave propagation
must of necessity be of a somewhat historical nature. The lit-
erature of the past half century contains the names of many who
have contributed their bit toward the understanding of a phe-
nomenon that has afforded mankind one of the greatest boons of
all time and which, in spite of its many complexities, has come
to be regarded as an every—day necessity.

It was Clerk Maxwell who first prepounded the theory that
electro—magnetic disturbances are propagated as a wave motion
through the dielectric. Although Maxwell's theory was presented
in 1864, it was not until 1887 that Hertz became the first to
prove by experiment that electro-magnetic waves do exist. The
first experiments of Hertz along this line consisted in showing
that high frequency reversals of electrical and magnetic forces
would produce sparks across small pieces of metal placed close
together. Hertz also carried out further experiments showing
that these disturbances were analogous to light waves. He proved
that a non-conducting surface placed between the source of the
disturbance and the bits of metal would not stop the passage of
energy but that a conducting surface would. He also proved by
the use of large mirrors and prisms that electro-magnetic waves

are reflected and refracted the same as light waves. Trouton

1037-15

carried this analogy further and proved that an electro—magnetic
wave polarized at right angles to the plane of incidence falling
on a refracting substance at an angle tan‘lu, where u is the re-
fractive index, would be totally refracted and none reflected.
With the wave polarized in the plane of inbidence, some of the
energy would be reflected whatever the angle of incidence. These
findings are, of course, in agreement with well—known laws of
ligfllt.

By Maxwell's theory the velocity of propagation of electro-
magnetic waves should be that of light. Hany experimental tests
and determinations of this value have been made and the results
check very closely with this theory.

Lodge and Righi, with various experiments and theories, ad-
ded much to the understanding of electro-magnetic waves and
their propafiation, but it was Marconi in 1895 who first made
practical use of these waves for the transmission of intelligence.
His first successful experiment was the transfer of a signal
over a space of one mile in London, England. He made.many other
tests in successive years until in 1901 he performed his historic
eXperiment of transmitting a signal across the Atlantic.

Wireless telegraphy was the only means of transmitting in—
telligence through space until means were developed to super-
impose sound modulation upon a continuous electro-magnetic wave.
Wireless then came to be known as radio and attracted the con-
centrated attention of a great many scientists and engineers with

the result that at the present time a high perfection of the art

of radio transmission has been reached. The various methods of

-3-

modulating the radio wave are not touched upon here for they have
as a rule no effect upon the prOpagation of the wave itself and
herefore have no place in this chapter. The universal use of
radio, however, has been the cause of much more study and conse-
quent knowledge of the prepagation of the radio frequency carrier.
Until 1926 the use of the radio spectrum was confined chiefly

to low frequencies and the wave was usually conceived as an
electro-magnetic disturbance traveling along the earth, causing

no permanent change in the transmitting medium and consisting of
two components; one magnetic with lines of force parallel to the
earth's surface, and one electro-static with lines of force normal
to and terminating in the conducting earth.

The most common analOgy and one which is still in use is

that of a pebble drOpped in water, the resulting motion traveling
out from the center in a series of circular waves, this motion
causing no forward motion of the water itself. The prepagation

of the wave motion is caused by the displacement of small par—
ticles of water, which in turn transfer this motion to the ad-
joining particles. Due to the inertia of the water, this displace—
ment occurs faster than the transfer of energy of motion and the
water piles up in a crest. By gravitational laws, the water now
tends to seek its own level, and due to this and because the par-
ticles of water possess inertia they move below the average level
and a depression is formed. This wave motion continues outward
at a velocity determined by the degree of inertia of the water
and to a distance determined by the initial energy and the co-

efficient of absorption. It should be understood that this wave

 

-4-

motion is a transfer of energy from one particle to another and
that each particle is only slightly displaced from its original
position.

In applying this analogy to the transfer of electro-magnetic
waves through a medium, we must then, assume a medium which is a
physical reality; a medium composed of small particles possessing
mass and inertia which have kinetic energy stored up in their
motion and which also have elasticity. Such a medium closely co-
incides with Faraday's theory of tubes of force.

With such a medium.surrounding the earth, one can conceive
of a wave motion set up by the reversals of current in an an-
tenna. These reversals create an alternately magnetic and electro-
static field in the immediate vicinity of the antenna. The mag-
netic and electro-static components of this induction field are
in both space and time quadrature. Not all the energy stored up
in the magnetic field is returned to the antenna but some of it
is used up in causing diSplacements of the particles composing
the medium. This displacement is transferred from particle to
particle and can be thought of as an electro-static charge which
in.motion creates a magnetic field. This is known as the radia-
tion field and as shown, has two components, magnetic and electro—
static. However, they differ from the components of the induction
field in that they are in space quadrature but in time phase.

There is no alternate building up and collapsing of this
fiEld but in the simplest case a spreading out of the field in
“Um form.of a wave motion of the same frequency as the current in
the antenna. This motion travels outward with the velocity of

light. The radiation field may be defined as energy which is lost

 

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(FROM Tau-,mAH)

 

to the induction field. It is this radiation field Which is
of use in transferring signals through space and which will be
fUrther analyzed in this thesis.

It has been proven mathematically and experimentally that
the energy of the induction field falls off inversely as the
square of the distance from.the source and that due to the spread-
ing out of the wave motion the radiation field falls off inverse-
ly as the distance.(l)

In addition to this spreading out of energy, there is a loss
to the radiation field through absorption of energy in the earth's
resistance, in an imperfect dielectric and in objects such as
trees and buildings in the path of the wave.

Experiment has nearly always been ahead of theory in radio

studies and as radio has come into general use many discrepancies

have been found from.time to time between theory and experiment

(1) For a classical mathematical proof, the reader is referred
to that of Dr. Dellinger in The Scientific Papers of Bureau of
Standards 3354, 1919. This and other early proof was based on
the theory that the earth is an isolated conducting sphere.

-6-

of radio wave propagation. Marconi first noticed in 1902 that
the night time wireless signal was of greater intensity than the
daytime signal. Theory was then prepounded that there might be

different paths along which the signal traveled.

KENNELLYFHEAVISIDE LAYER:

The idea that there might be an ionized upper atmospheric
layer was first advanced by Kennelly in 1902. A short while af-
terward, the same idea was suggested independently by Heaviside.
Since then the theoretical existence of such a layer has been
the instigation of much research, and the mass of data now avail-
able proves conclusively the actual presence of such a layer and
indicates that the variable nature of the layer accounts for many
of the vagaries of radio transmission.

This layer for a long time was known as the Heaviside layer
and is still referred to by this name by some writers. However,
most literature now gives Dr. Kennelly his just due and uses the
term Kennelly-Heaviside layer.

The theory that the electro-magnetic wave reached the re-
ceiver not only from the ground wave but also from a sky wave
which was reflected from the Kennelly-Heaviside layer became gen-
erally accepted. However, there seems to have been very little
experimental research of note regarding the prOpagation of the
waves until 1910, when Dr. Austin of the United States Bureau of
Standards started a series of studies. From.the work carried on
by him in 1910 and 1913, the well-known Austin-Cohen formula was
derived. Dr. Austin's experiments were made on a frequency of

600 kilocycles and his observations were made on the path of the

wave over sea water.

While the work of Dr. Austin did not take into consideration
the presence of the Kennelly-Heaviside layer, his work did excite
much comment and led to much mathematical research tending to
prove that in order to agree with some of his experimental data
there must be reflection or refraction from an upper ionized layer.

Eccles advanced a theory in 1912 which strengthened this
idea. He assumed a total reflection of the wave on the basis of
a sharp definition between a region so heavily ionized that the
wave could not penetrate and the lower atmospheric layer adjacent
to the earth. This idea of a single heavily ionized layer giving
complete reflection seems to have been the popular belief until
1924, when Larmor presented his theory of refraction of the wave.

Larmor's theory was one of refraction of the wave with
little absorption due to the presence of free electrons of long
free path within the Kennelly-Heaviside layer. He submitted a
series of classical equations to prove his theory. These equ-
tions gave a very close agreement with what experimental data
vms available at that time and were accepted as holding true for
all frequencies. Larmor showed by these equations that waves of
low frequency would be bent around the earth due to the ionic
gradient of the atmosphere, that this effect increased with the
square of the wave length and approached zero for the very short
waves.

In 1925, however, both Remartz and Taylor working indepen-
dently, disproved experimentally, Larmor's equations as far as

their application to short waves was concerned. Taylor, working

 

 

 

-8-

with wave lengths of 16, 21, 32 and 40 meters with 5 kilowatts
in a normal antenna, found that the signal decreased with dis-
tance until at 100 miles it could not be detected. A zone of
silence followed and then another signal zone appeared. The two
zones were not sharply defined but were separated by a flicker
zone where the signal was both weak and intermittent. In daytime
he found that these signal zones were spaced differently for
different wave lengths and were 1300, 700, 400 and 175 miles
for wave lengths of 16, 21, 52 and 40 meters, respectively. These
distances were referred to as skip distances. At night they were
found to average roughly from 3 to 4 times the daytime distance.
These measurements were performed with the assistance of many
observers scattered over an area represented by a radius of some
1500 miles and were necessarily of a rough nature. However,
enough reports were obtained to show that short waves were re-
turned to earth from the ionized layer. These findings were of
course in direct opposition to Larmor's equations for short waves.

Appleton, a few months later, explained this disagreement
by showing that the free electrons would move in spiral paths
due to the earth's magnetic field and assumed that there was a
certain critical frequency beyond which Larmor's equations did
nOt hold in their present form. It was shown that by the inser-
tion of a critical frequency term the equations would check with
GXperimental data at both ends of the spectrum.

FUrther support of this theOry of a critical frequency was
found at this time in an independent hypothesis by Nichols and

Shelleng. They had observed from experimental data that fre-

 

 

 

 

 

 

-9-

quencies in the neighborhood of 1400 kilocycles showed great
irregularities in radio transmission. They explained this phe-
nomenon by showing the effect of the earth's magnetic field at
this frequency.

A free ion moving in the earth's magnetic field has a force
exerted upon it which is at right angles to its velocity and to
the magnetic field. The resultant oscillation of the free ion
is a vector combination of the free oscillation and the forced
one and is in the form of a spiral whose projection on a plane
is an ellipse. here is a certain critical frequency there the
velocities of the free and forced oscillation become very large.

This critical frequency

.. H
Fc-‘Zfifi (W

where H is in electro-hagnetic units

e is in electro-static units

m is mass of ion

0 is velocity of light
Assuming the intensity of the earth's magnetic field to be 1/2
gauss, this critical frequency is 1400 kilocycles. This motion
of the free ion forms a convection current which will react upon
the electre-magnetic wave and change the velocity of propagation
of the wave. Ions in rotation do not store up energy in a di-
electric but use up energy in thermal agitation and in re-radia-
tion. The velocity of the spiral oscillations of the free ions
at the critical frequency assume such proportion that the number

Of collisions with the particles composing the electro-magnetic

-10-

wave is very great, and the consequent rapid changes in phase
result in a dispersion of the wave and much greater attenuation
than is suffered by waves of a frequency above and below this

critical point.

METHODS OF MEASUREMIN :

There has been much intensive study of the properties and
action of the Kennelly-Heaviside layer since 1925. The greater
part of these studies have had to do with the height of this layer.
There are several methods in use by which the height may be de—
termined. The one most commonly used is that devised by Breit
and Tuve.

This is known as the "pulse method." The first experiments
of Breit and Tuve consisted in operating a transmitter to send
out interrupted continuous waves of 1/1000 second duration. The
ICW was obtained by supplying the oscillator with direct current
plate voltage and the power amplifiers with 500 cycle alternating
current voltage. The wave from the transmitter was first inves-
tigated with an oscillegraph and the transmitter adjusted until
the wave was accurately single humped. A superheterodyne receiver
was set up at a distance of eight miles from the transmitter and
the signal was detected, amplified and oscillographed. A camera
was set up to take photographs of the oscillograph in order to
:make a study of the signal.

In this method, he signal from the ground wave reached the

1

receiver first and would be closely followed by a reflected signal
from.the Kennelly—Heaviside layer. The difference of time between

the occurrence of the two humps could be accurately measured on

-11...

the oscillogram. Assuming the signal to be reflected from a
point on the surface of the layer, and knowing the distance from
the transmitter and velocity of the signals, the height of layer
could be computed by triangulation.

"N

The transmitter of the Naval nesearch Bureau station NKF
was used in these experiments. The wave lengths used were 71.5
and 41.7 meters. The experiments were made in June and September,
1926. These experiments indicated a height of layer ranging

from 90 to 140 kilometers, the average being 125 kilometers.

The experiments of Breit and Tuve were the start of many
researches along this line, some of the most notable being those
of Dr. A. H. Taylor, Kenrick and Jen, Shaeffer and Goodall and
Appleton and Barnett.

The methods of Kenrick and Jen were essentially those of
Breit and Tuve, with the exception that the transmitters were
modulated by a multivibrater by means of which they were able to
obtain transmission of single sharp and well separated pulses.
This increased the accuracy of measurement on the oscillogram.
Frequencies of 4455 kc. and 8870 kc. were simultaneously trans-
mitted from NKF at Washington, while the receivers were set up
in Philadelphia.

Schaeffer and Goodall used frequencies of 1604 kc. and 5088
}{C. in early tests. The transmitters were located at Deal, N. J.,
zand the receivers 15 miles away. The two transmitters were simul-
‘taneously modulated, the pulses being obtained by a contact wheel
ruin by a synchronous motor. The duration of pulse was .0005 see.

aiui the separation 1/50 sec. The received signals were fed to

-13-

separate vibrators of a string oscillograph while a timing wave
from a 1000 c. tuning fork was imposed upon a third vibrator.

In later tests, the string oscillograph was changed for a
cathode ray oscillograph, the separation between receivers and
transmitters was reduced to l kilometer, and frequencies of 1604,
2598, 5256, 4795 and 6425 kc. were used. This test was more com-
plete than any yet reported, representing as it did 500 hours of
observation.

The most interesting thing in the methods of this test was
the use of the cathode ray oscilIOgraph and the manner in which
it was calibrated for use.

A sixty cycle timing wave was used and the amplitude of its
trace adjusted to extend across the oscillograph screen. This
spreads out a time of 1/120 sec. over about 5% inches. As the
reflections occurring during the first quarter cycle are the ones
most under observation in studies of layer height, this portion
of the screen was scaled twenty parts to the inch. Each division
was marked in the corresponding layer height computed by the
usual method of difference in time between ground pulse and re-
flected pulse. The start of the ground pulse was shifted to co-
incide with the zero of the timing wave by means of a phase
shifter in the timing wave voltage supply. It was found to be
easy to read the scale to 1/2 division, which would represent an
accuracy of between 12 km. for values between the height 100 to
550 km. The second quarter cycle trace of the timing wave was
also present slightly separated from the first trace and the

'fiflrd and fourth quarter trace could be observed by a reversing

-13..

switch so that virtual heights up to 2500 km. could be observed
if desired.

.By this method the slow process of photographing and devel—
oping of film could be eliminated and rapid and continuous
checks of layer height could be made. The observer would report
by telephone the various heights as shown by the reflected pulse
signals along the timing scale and thus was saved the trouble
of recording the data.

The method of Appleton was considerably different from the
pulse method. A continuous wave was transmitted and the fre-
quency was gradually changed. As the frequency changes, the re-
ceived signal from the reflected wave goes in and out of phase
with the received signal from the ground wave. The in and out of
phase relations are delineated on the oscillograph by maximum
and minimum amplitude of signal. Knowing the increment of fre-
quency required to produce a change of phase of the received signal
by 180 degrees, one can compute the layer height.

Another interesting method of computing the height of layer
has been demonstrated by Mirick and Hentschel. In this case, the
transmitter was mounted on an aerOplane. The plane was flown in
a straight line between theU. S. Iaval Base at Anacostia, D. 0.,
to Havre de Grace, Hd., a distance of 150 miles. The speed of
the plane was kept constant and the ground speed computed from
position reports radioed from the plans. Two flights were made.
A frequency of 2725 kc. was used on one flight and a frequency
of 5000 kc. used on the other. Continuous field intensity measure-

nmnts were made and recorded on a moving chart. The results were

based upon the theory of interference patterns between ground and

sky wave.

length of

-14..

As the plane progresses, the difference between the

path of ground wave and sky wave changes, resulting in

maxima and minima peaks of intensity. The height of layer is

computed from the formula:

he

where h

V:
f =

X:

A:

 

XI EV—
HAL-Ix)
F
height of layer
velocity of plane
frequency of intensity peaks
distance of plane from measuring equipment

transmitter wave length

The measurements were all made around midday,

Hafsted and Tuve used still another variation of the inter-

ference method by coupling the output of the crystal controlling

the transmitter frequency to the receiver and noting the differ-

ence in the intensity of the received signal. This method was

devised for the purpose of detecting continuous changes in the

height of

length of

layer. By theory, if the layer stayed constant, the

path was the same and the phase relation of the two sig-

nals and the intensity of the signal at the output of the receiver

remained unchanged. Any change in layer height caused variation

in the phase relationship of the two signals and a consequent

change in
change as
moving up

the layer

intensity. However, it has been pointed out that this
indicated by the phase change may occur through the layer
and down as a whole or it may be that the lower part of

remains fixed and the ionic gradient of the layer changes.

-15-

In all of the above description of methods used in computing
the height of the Kennelly-Feaviside layer, the terms height of
layer and reflection from layer have been used. In all cases the
height has been computed on the assumption that the layer was so
heavily ionized that radio waves could not penetrate it and were
Completely reflected and that acCording to the physical laws of
reflection the angle of incidence equaled the angle of reflection.

In line with Dr. Kennelly's hypothesis presented in 1913,

Observations by many trained researchers indicate that the Kennelly—
thaviside layer is a heavily ionized region in the upper atmos-

Ifiuere due to ultra-violet rays from the sun. They have also shown

«.4

ttuit radio waves do penetrate this region and are refracted dox
WE1rd in accordance with Larmor's theory, instead of being com—
Ifiletely reflected. Hence the term height of layer is rather am-
biajuous, inasmuch as the layer has thickness. Th's thickness is
determined by the point at which the wave first starts to bend and
'the highest point in its trajectory. Therefore, the term "virtual
height" of layer is used to designate the apparent height to
'Winch the wave reaches when computed on the basis of simple re-
3f1ection. The virtual height is always higher than the actual
lleight.
Not knowing the exact nature of the degree of ionization of

'this layer makes it difficult to compute the exact path of a ray.
lThe usual method has been to assume a certain ionic gradient and
Solve for the height of layer that will agree with experimental
data. Breit and Tuve proved that with a certain assumed gradient

Of a refractive index of the layer it would require the same time

for the ray to traverse the trajectory of a parabola as the dis-

 

 

 

 

 

 

-15-

tance along the sides of the tangent triangle. The differential

equation of such a path is

 

 

ol .. n“: _.
alt—[mus ' (3)
n

 

Kenrick and Jen have added further analysis of the path and
show that the virtual height as computed by the reflection theory
is just twice the distance above the point where the wave begins
to be refracted as the highest trajectory of the path when com-
puted by the refraction method.

There are certain limitations in the frequencies which can
be successfully used in probing the upper atmosphere. Frequencies
above about 6000 kc. have not proved successful because the near-
est point where the wave returned to earth was out of the ground
wave range and therefore the difference in time of paths could
not be noted. Too low frequencies will not penetrate the layer
but will be bent around the earth in the region between the layer
and the earth. It has been suggested that this region also has
an ionic gradient, the ionization being enough to refract the low
frequencies but not the higher, although in the latter case it
nay cause some attenuation. Frequencies around 4000 kc. have been

used to the greatest extent in determining the layer height.

-17-

The results of all the measurements by different researchers
have been in close accord considering the variable nature of the
Kennelly—Heaviside layer. These results show a marked diurnal
and seasonal variation, the lowest height being found shortly
after noonday and the highest about an hour before sunrise. The

height is greater in winter than in summer. The usual diurnal

variation is shown in Fig. 3.

 

This diurnal chart proves conclusively the part the ultra-
violet rays of the sun play in this change of apparent layer
height. The sharp discontinuity shortly before sunrise is be-
cause the sun's rays touch the higher region first, increasing

the ionic content and decreasing the effective height of layer.

E AND F LAYERS:

Appleton, in 1926, experimenting with 400 meter wave lengths,
found an apparent height of layer of from.90 to 130 kilometers
in summer and during the winter he noted heights of from.250 to

500 kilometers in the period of three hours before dawn. He

-18...

IEmsoned that there might be two instead of one ionized layer
and'flmt in.this period before dawn recombination set in in the
lower layer, permitting the wave to penetrate to the higher, more
heavily ionized layer.

This theory is supported by later measurements on the layer
where multiple echoes were noted. In many cases these occurred
in.multiple time relation to the difference between the ground
wave signal and the first signal from.the layer and were explained
on the basis that they were multiple reflections from.the layer
and that they constituted a check on the accuracy of the first
measurement. However, many of these were not in multiple relation
and could not be explained on any other basis than that of possi-
ble reflection from a higher layer. Occasionally signals of longer
delay were noted which seemed to be multiple reflections from.the
higher layer.

As more and more data was accumulated on different frequencies,
it appeared that there are critical frequencies above which the
Waves could penetrate to the higher layer. These critical fre-
quencies are not constant but change with the condition of ioni-
zation of the lower layer. It was then postulated that there are
also critical frequencies above which the waves could penetrate
the upper layer and would not be returned to earth.

It is now generally accepted that the above theory of two
ionized layers is true. The lower layer has been designated by
Appleton as the E layer and the upper layer as the F layer.
Chapman advances the theory that the F layer is of atomic oxygen

ionized by the ultra-violet rays of the sun, while the E layer

 

 

 

-19..

is of atomic oxygen ionized by non-wavy corpuscles shot out by
the sun. However, the idea of ionization by neutral particles
seems to have been disproved in the observation of the solar e-
clipse of August 31, 1932. According to theory, these corpuscu-
lar radiations may obtain a velocity of 1600 km. per second, and
a decrease in ionization due to the eclipse of these particles
would be noticed about two hours before the light eclipse. No
such effect was observed in any part of the world. There was a
decrease in the lower layer ionization of about 40% and in ioni-
zation of the upper layer by 30%. This decrease seemed to be in
phase with the light eclipse. Hence it is thought that ultra-
violet rays from the sun are responsible for the greater per-

centage of ionization in both layers.

;L:_A_GNETIC S TOPMS :

In the course of many studies of the upper atmospheric re-
gions referred to by some as the ionosphere, it became apparent
that there were many irregularities in the behavior of the ioni-
zed layers. While in general the diurnal variations were of a
like nature from day to day, there were periods when the action
was very erratic. In search of a solution for these irregular-
ities, the experimenters turned to terrestrmd magnetism. Attempts
to correlate magnetic storms and changes in radio transmission
have met with considerable success.

The study of the cause of magnetic storms and their effect
on radio transmission has been carried out in particular on trans-
Atlantic radio circuits on both high and low frequencies. The

procedure in most cases has been to measure the field intensity

 

 

-20-

at short intervals, of distant radio stations whose radiated

power was known to be constant within close limits. Some obser-
vers at the present time use automatic field intensity record-

ing equipment which keeps a continuous record. These measurements
are averaged by the moving day method, thus giving a mean daily
observation. These are compared with measurements of the earth's
magnetic field intensity and sunspot numbers.

Work of this nature has been carried on by the U. 8. Bureau
of Standards, the Bell Telephone Laboratories, the RCA Communica-
tion Co., and by foreign observers for a number of years. The
observations of Dr. Austin of the Bureau of Standards in particu-
lar date back to 1914.

Any observations of the solar state and its correlation with
terrestrial magnetism and radio reception must necessarily ex-
tend over a number of years in order to determine the average
trend. Many irregularities and discrepancies in the daily obser-
vations of different researchers are noticed which may be due to
purely local disturbances and to possible variations in trans-
mitting or measuring equipment itself. These smaller variations
smooth out in a series of averaged results and the comparatively
true relationship can be observed. For this reason articles
containing definite information are of relatively recent origin.

It is now almost certain that magnetic storms are sudden
thuluxes of ions in the earth's atmosphere caused by flashes of
\fltra-violet rays from.the sun. Observation on the behavior of
<lurrents in the crust of the earth seem to indicate that these

murents are induCed by these clouds of ions because of transient

 

 

 

 

-21..

surges set up while they are equalizing throughout the ionized
layers. The effects of these sudden influxes are immediately
noticed by changes in radio transmission, in the earth's magnetic
field and in earth currents, but it takes several days for con-
ditions to return to normal.

It has been determined that although there are some irreg-
ular disturbances, in general, magnetic storms occur in 27-day
cycles. This corresponds to the rotation of the sun in the region
of the greatest number of sunspots. The sunspot numbers them-
selves increase and decrease in eleveneyear cycles. Magnetic
storms are also more prevalent in summer than in winter.

The work of all observers over a long period of time shows
a direct correlation with sunspot numbers, magnetic activity

and radio reception. This is shown in Fig. 4.

IIIIIIIIIIIIIIIIII
EIIIEIS'“!“E"EIEE

 

 

 

-22..

The effect of magnetic storms is just the Opposite on low
frequencies from that on high frequencies. The daytime inten-
sity of low frequencies is sometimes increased by as much as 75%,
While the night-time signal is decreased. High frequency trans-
mission is sometimes blocked entirely during a magnetic storm
and always suffers a dr0p in field intensity. This effect is
noted to a greater extent in east to west transmission than in
north to south. At the government frequency monitoring station
at Grand ISland, Nebraska, it was often the case that stations
from South America could be received with good volume while those
from.Eur0pe were completely blanketed by magnetic disturbances.

This difference between the action of the high and low fre-
quencies during magnetic storms may be due to the fact that the
higher frequencies in penetrating to the higher regions encounter
these clouds of electrons first and suffer great absorption,
while the lower frequency waves will be affected only in case
the influx is great enough so that the downward diffusion reaches
the lower layer. It is evidently true that higher frequencies
are affected i mediately while the effect on the lower frequen-
cies shows a lag. This downward drift of electrons would account
for the decreased night-time signal on low frequencies but will
not explain the greater daytime signal.

The Kennelly-Heaviside and Appleton layers are evidently in
la constant state of turbulence due to uneven degrees of ioniza-
'tion. The old physical conception of a cold, immobile upper

atmOSphere has now been discarded in favor of the idea of one

which is highly mobile, is hot in the upper reaches in daytime
and cold at night and subject to high winds. The various sources
which contribute to the ionization have been listed by Skellett
as follows:

Energy received byothe

 

 

Sources of ionization earth in ergs cm"‘“sec"l
Ultra-violet light from the sun . 28.35

" " " " " full moon .000044

" " " " " stars (approx.) .014
Cosmic rays .00031
Keteors average normal day: A. M. .00024

" " " " P. M. .00012

, Meteor showers (A. M.) up to 2.4

It would seem that none of these except the sun and possibly
meteor showers would affect radio transmission. Shaeffer and
Goodall made measurements of the height of layer during the Leonid
shower of November, 1931, but were unable to determine any great
effect on layer height which could be directly attributable to

the shower.

ECHO SIGNALS:

 

In the process of studies of the ionized layers by pulse
methods, there were observed many instances of greatly retarded
echoes. Stormer at Oslo, Norway, and Van der Pol at Eindhoven,
Holland, noticed retardations as long as 15 sec., while Hals noted
retardation of over 3 min. Taylor has also made many experiments
on echo signals. There seem to be three types of echoes mentioned

in.the literature:

let. The echoes used in measuring height of layer which are
Immsured in thousandths of seconds.

2nd. Round the world echoes which normally require a time of
1/7 second.

3rd. Echoes of long delay from 4 seconds to several minutes.

Stormer has endeavored to explain these echoes of long delay
on the theory that streams of electrons from interstellar space
are deflected by the earth's magnetic field and form a huge space
in.the shape of a torus, within which no electrical particles
exist. Radio energy penetrating the layers enters this space and
is reflected from the outer walls. Van der Pol and Breit dis-
prove this on the basis that such long retardation would represent
a distance of signal path which is comparable to the distance to
the moon and back However, Pedersen has aligned himself defi-
nitely on the side of Stormer.

Van der Pol prepounded the theory that due to low group
V810city the signal is retarded. To understand this theory, one
must have a clear conception of group velocity and phase velocity.
ACcording to Pedersen, the group velocity is the velocity with
Which the energy of the wave travels. This velocity can.never
exceed that of light and can approach zero as a limit under cer-
tain conditions of electron density and frequency. The phase
Velocity is the velocity with which the phase changes along the
Path of the wave. The phase velocity is determined by the number
or electronic and ionic collisions occurring in the path. Each
time a collision occurs, energy is subtracted from the wave and
is Used in re-radiation in a new phase. Thus the phase velocity

determines the attenuation of the wave in the ionized layer. In

 

 

 

 

certain conditions of frequency and electron density, the phase
velocity may become infinite and the group velocity may approach
zero.

Appleton attacks this theory because of the large attenuation
which would accompany a delay of 15 seconds. Such attenuation
was not apparent on the measured signals. The evident difficulties
in making either of these theories entirely agree with experimental
data have left this an open question.

Taylor has observed many shorter time echoes which he thinks
are reflections from hilly country and reflection returned to the

layer from points outside the first reception zone.

FADING AND POLARIZATION:

 

One familiar phenomenon in radio wave propagation is that of
fading of the signal. The first study of fading of note was that
undertaken by the Bureau of Standards in 1926. Observations were
made on Station WGY at Schenectady and KDKA at Pittsburg from
several points in the eastern and central states. Since then
there have been many observations of fading phenomenon on frequen-
cies throughout the radio spectrum. The findings of these inves-
tigators are in general as follows:

1. Fading is more pronounced at night than during the daytime.

2. Fading is more pronounced on high frequencies than on low
frequencies.

3. Daytime fading often occurs on high frequencies, but is
not generally encountered on low and broadcast frequencies.

4. On low and broadcast frequencies, there is a slow period

of fading just after sunset at the receiving station.

-25-
5. Fading is greatly increased during periods of magnetic
storms.
The causes of fading are divided into two general cases:
a. Wave interference.
b. Changes undergone by the indirect wave.
One of the most common types of fading noticed in the broad-
cast band is that caused by the in and out of phase combinations
of the ground wave and sky wave. The area around the station

is divided into zones as shown in Fig. 5.

N‘\XIMUP1L|HIT
btRViLEARfA
ABOUT up Mn t 3

 

In the first zone adjacent to the station, the ground wave
Predominates and there is usually no fading. In the next zone
whichais called the zone of intolerable fading, the ratio between
the Signal intensities of the two waves are in the neighborhood
01' three to one and objectionable fading occurs. This zone ex-
1Ends cmt to where the ground wave intensity is very low and the
31W Wave predominates. This next area or zone where there is

°nlY'the sky wave present may extend to great distances and a zone

-27-

of steady signal or bad fading may occur, depending on the con-
dition of the Kennelly-Heaviside layer. The distance to which
the ground wave predominates depends to a great extent upon the
radiated power in the horizontal plane, and to the frequency used.
Roder has shown, however, that there is a limit to the extent of
this zone regardless of the power used. At the limiting distance
of about sixty miles, the sky wave will always be equal to the
ground wave assuming normal radiation along sky paths. The zone
in which freedom from fading is experienced is generally greater
in daytime than at night, due to the night time increase of sky
wave signal intensity while the ground wave intensity remains
unchanged.

Fading in the region where the sky wave predominates may be
caused by the in and out of phase combination of two waves arriv—
ing from different paths in the layer or from turbulent conditions
in the layer.

Fading has been noted by the author on broadcast frequencies
which have evidently been caused by the ground wave taking dif-
ferent paths. While making a field strength survey on Station
WBXP of the Westinghouse Electric Company at Pittsburg, severe
fading of about 15 second duration was noticed on the opposite side
of Mt. Washington from the station which was located at Saxonburg,
several miles north of Pittsburg. While this was probably far
enough away so that fading might have been caused by intermingling
of sky and ground wave, the fact that there was no fading on the
Eflde of Mt. Washington toward the station led us to believe that

flkifading was caused by part of the ground wave taking the path

-28—

through the mountain and part taking the path over and around
the mountain. This would cause enough ratio of path difference
to wave length to cause out of phase components.

many instances of close-in fading were observed near Butte,
Montana, on a recent survey. Butte is just three miles west of
the Continental Divide and the terrain is very rough and mountain-
ous in this region. In one case, on measurements made in a canyon
just east of the Divide, severe fading of about 2 seconds duration
was experienced in the daytime. Moving the receiving set a short
way resulted in a different period of fading. In this case the
fading was undoubtedly caused by reflected waves from.the canyon
walls. It was noted on this survey and has been noted by other
observers on low and intermediate frequencies that there is a
type of fading which occurs just after sunset. This dip in sig-
nal intensity may persist for twenty minutes and then the inten-
Sity rises rather rapidly to the usual night time value.

According to Kennelly, this is caused by the position of the
Sunset wall. It seems reasonable that this dip in signal inten-

Sity may be caused in the following manner.

HOuFo \fil “ORE surf l. I HOURb ACFFH QquET

Flb.C§

 

 

 

 

-39-

As the sunset shadow plane increases in height, ionization
decreases in the lower layer due to the cutting off of ultra-
violet rays and the signal intensity increases. Then, for a
short time there is a replenishment of ions from the upper layer
until the shadow plane rises to this greater height. See Fig. 6.

Another type of fading which is noticed a great deal on
modulated frequencies in both broadcast and high frequencies is
known as selective fading. This is indicated by "mushing," or
distortion of the audio components. In this type of fading, radio
frequencies which are separated by audio frequency differences
fade at different rates and cause both fundamental and harmonic
distortion of the audio signal when detected.

The Bell Telephone Laboratories have made an extensive study
of this type of fading on short waves and have noticed that radio.
frequencies of only 170 cycles separation are affected differently.
Continuous observation seems to indicate that selective fading is
periodic in its recurrence. It is noticed less in summer than in
winter months.

Most investigators agree that the chief cause of fading can
be credited to changes undergone in the path of the sky wave.
Aside from changes caused by varying absorption and interference
between waves traveling by multiple paths, there is another effect
which causes much fading and direction shift.

This is a rotation of the plane of polarization of the wave.
According to Appleton, polarization of the wave is caused by
double refraction in the ionized layers due to the earth's magnetic

field. This does not seem to be a permanent shift in plane pola-

-50-

rization but rather a continuous shift and results in either
circular or elliptical polarization, depending upon the ratio of
energy and phase relation of the two components. Alexanderson
has shown that a wave starting out horizontally or vertically
polarized will stay that way in a homogeneous medium, but that a
wave starting out at an angle of 45 degrees will have a continu-
ously rotating plane of polarization. By polarization is meant
the position of the electric vector with respect to the direction
of travel of the wave. A vertically polarized wave has the elec-
tro-static lines of force at right angles to the motion of the
wave. A horizontally polarized wave has the electro-static lines
of force in the plane of travel. The ground wave is vertically
polarized, otherwise the lines of force would be shorted out by
the conducting earth. he sky wave is horizontally polarized until
it strikes the upper layers where polarization may take place.

The theory of double refraction of radio waves in the ionized
layers is known as the magneto-ionic theory. Appleton and Ecker-
sley have both noted that the waves have become split and that
the components have become circularly or elliptically polarized in
Opposite directions. The magneto-ionic theory suggests that,
looking in the direction of polarization, the right-handed compon-
ent should become more attenuated than the left in the northern
hemiSphere. This agrees with Appleton's observations but is cp-
posed to Eckersley's. This question is yet controversial.

The phenomenon known as "night effect," in which the direction
of the signal appears to be shifted after sunset, is caused by

polarization effects experienced by the wave in the upper layers.

-31-

This apparent direction shift causes errors in bearings taken by
radio compass. In the case of radio beacons, this is compensated
fpr at the transmitter.

All frequencies in the radio spectrum are subject to fading
with the exception of ultra high frequencies within the range of
about 35 to 100 megacycles and within the "line of sight," or
optical distance.

ULTRA HIGH FREQUTNCIES:

This extremely high frequency band is being investigated at
the present to discover its adaptabilityfbr television, police
broadcasting and short range telephone communication.

The Bell Laboratories and the RCA Victor Company are especi-
ally interested in ultra high frequency transmission, and during
the past year they have added much to the knowledge of the char-
acteristics of these waves. In general their experiments have
Shown no great variation from what would be expected of waves be-
tWeen high frequencies and light waves from theoretical considera-
tions.

In many ways these waves behave as waves of lower frequencies.
The field intensity in open space falls off inversely as the dis-
tance with little absorption. Near the ground absorption becomes
'Very apparent, with the higher frequencies showing the greatest
attenuation.

The waves appear to be above any critical frequency of the
uDper layers as no signals are returned from them. However, inter—
ference is experienced between the direct ray and rays reflected

from the earth. Due to the unchanging nature of the reflecting

 

 

 

 

-52..

medium, this interference does not cause fading at one point,
but there will be alternate regions of high and low field inten-
sity. These Lloyd's fringes have also been observed in the
neighborhood of trees, suggesting re—radiation.

In the neighborhood Of large buildings, there seemed to be
much diffusion as in some cases signals were of good intensity
when there were many buildings in the line of sight. Moving
Objects in the light Of sight could easily be detected by their
effect upon the field intensity meter.

Although in general, reception was best within the Optical
distance, it has been demonstrated that the necessity of having
to be within this zone has been greatly overestimated. Signals
of good intensity have been received far below the Optical dis-
tance due to diffraction and refraction of the wave. The differ-
ence between very long wave and ultra short wave refraction is
that refraction of long waves occurs in the region between the
earth and the Kennelly-Heaviside layer, a distance of around 125
km., while refraction Of the short waves occurs in a region within
one kilometer of the earth.

Measurements made on the RCA transmitter located on tOp Of
the Empire State Building in New York City were carried out to a
distance Of 280 miles. The television transmitter operates on a
frequency Of 44 megacycles and an output power of 2 kilowatts.
The sound transmitter Operates on a frequency of 61 megacycles and
a power of one kilowatt. It was found that the average service

range included New York City and urban territory, while the inter-

-33-

ference range extended to a distance of one hundred miles. much
fading was noticed on these frequencies outside of the optical
range.

With high antennas, very little difference is noticed between
the signal intensity Of a vertically or horizontally polarized
wave, but with low antennas the efficiency of the vertically

polarized wave was much higher.

SUMMARY}

Early radio communication and experimentation was carried on
with low frequencies from about 500 to 100 kc. The radio spectrum
has since been extended to include a frequency range of from 10
kc. to 400 megacycles. This frequency range is in general divided

into four bands, viz:

Low - 10-500 kilocycles
Medium. - 500-3000 "

High — 5000 kc. ~ 35 megacycles
Ultra High - 35-400 megacycles

Within the medium frequency band, there is a band including
frequencies from 550 to 1500 kc. which on this continent is called
the broadcast band.

It may be well to recapitulate a little in regard to the prep-
agation of the waves within the different bands. In the low di-
vision the received energy is entirely transmitted by ground waves
which bend around the curvature of the earth. Due to the fact
that ground absorption is very low for these frequencies, they may
extend to great distances from the transmitter.

The reception of frequencies in the medium.range may be either

-54-

by the ground wave or by a sky wave which is refracted back to
earth from an ionized region known as the E or Kennelly-Heaviside
layer, or from an upper layer known as the F or Appleton layer.
The average height Of the Kennelly-Heaviside layer has been de-
termined to be around 125 kilometers, while the average height

of the upper layer is around 230 kilometers.

Daytime reception Of medium frequencies is generally ground
wave reception. The early formulas Of Dellinger, Zenneck, Sommer-
feld and othersstill hold for ground wave transmission.

High frequencies travel entirely by sky paths, being refracted
back to earth from one or the other of the layers. From.which
layer the refraction takes place depends upon the frequency of the
radio wave, the time of day and the state of ionization Of the
different layers.

Ultra high frequencies in general tend to travel along straight
Slime paths. They are usually free from fading and polarization

EEffects within the Optical distance.

The differences of propagation between these four divisions
(X? frequencies are not sharply defined and the characteristics
“Ray overlap considerably. The scope of this thesis in succeeding
<Ihapters is limited to the discussion of transmission character-
3iStics and to the measurements of field intensities within the

'broadcast band.

 

 

 

Chapter Two

HISTORICAL.

SOME EARLY DEVELOPMENTS IN FIELD INTENSITY EEASUREMENT:

The first radio field intensity measurements were made in
1905 by W. E. Duddell and J. E. Taylor. The method used by them
was that of observing the current in a receiving antenna by means
of a galvanometer. These early observations were made on a fre—
quency of 1500 kc. on transmission over water between the steam-
ship Monarch in the Irish Sea and a land station. Some overland
observations were also made. In 1906 Tissot made similar measure—
ments using the same methods.

There seems to have been little other activity along this
line until the more comprehensive experiments of Dr. Austin in
1909 and 1910 from which the well known Austin-Cohen theory was
derived.

These tests were made on radio transmission over salt water
between the Fessenden station located at Brandt Rock, twenty miles
south of Boston, and the U. S. Cruisers Birmingham and Salem.
Keasurements were made of the received antenna current and all
formulas were develOped in terms of antenna height and current

at both transmitter and receiver. The method of measuring the

received current is shown in Fig. 7.

-55-

 

Strong signals were measured by a hot wire ammeter circuit
inductively coupled to the antenna and weak signals were measured
by a shunted telephone circuit capacitively coupled to the an-
tenna. The telephone circuit was calibrated by a buzzer circuit
inductively coupled to the antenna and a thermo galvanometer in
the antenna circuit. The standard of audibility was arbitrarily
chosen as the signal level which would give clear differentiation
between dots and dashes. measurements made by this method are
necessarily of a low degree of accuracy because the arbitrary
standard changes with reception conditions and with different ob-
servers. It is rather remarkable that the results of these meas-
urements check so closely with the results of present day measure-

ments. It is a remarkable commentary on the ability of Dr. Austin.

-57-

These early measurements were all iade of the received current
in a flat top antenna. At that time the use of 100p antennas for
reception of radio signals was limited largely to theoretical
discussion. Fitzgerald and Fleming in 1907 and Picard in 1909
were apparently the only ones who had given much attention to an-
tennas of this type. Braun in 1915 published an extensive article
on the use of coil antennas which created a great deal of interest
and during the war this type of antenna was used extensively for
direction finders.

In 1915 the develOpment of the coil antenna as a receiving
antenna was begun by the U. 8. Bureau of Standards and in l9l7
a series of measurements to check formulas for antenna to coil
transmission were started. These measurements were made by the
audibility method and like the previous attenuation measurements
were only relative ones.

It was not until after the advent of broadcasting that a
great deal of interest was attached to methods of making field
intensity measurements in terms of a standard unit. In this
country the work of Bown and Gillett, Bown, Hartin and Potter,
Espenschied, Jensen and Friis and Bruce was outstanding in this
line in the years 1924-1926. The work of Bown, Hartin and Potter,
and Espenschied in making field intensity surveys of stations
WEAF in New York and WCAP in Washington was of especial interest
in determining a standard of broadcast reception. The work of
Jensen and Friis and Bruce was confined chiefly to the develop—
ment of equipment to accurately measure field intensities in

microvolts per meter.

-38—

"rim Tr. v

PIONEERING WORK g§_gnpma§p;o DIVISION OF The U. s. Darinrnlur
OF commRCE:

 

At this time broadcasting in the United States was under
the supervision of the Radio Division of the United States Depart-
nmnt of Commerce. Frequency allocation and licensing was handled
by this department until 1925 when in a test case the court ruled
that the department had never been granted the authority to re—
fuse licenses. The result of this decision was a chaotic condi-

tion in the broadcasting field. Stations were arbitrarily jumping

a

up.

U

to different frequencies and many new stations were startinr

This condition was the direct cause for the creation of the Federal

Radio Commission in 1926. This commission was originally intended
to be an appellate body alone, while the Radio Division continued
in the capacity of a law enforcing body.

The conditions of severe interference be ween stations re-
sulting from the breakdown of governmental authority brought at-
t<Ention to the fact that greater knowledge of the fields laid down
EN? radio transmitters was necessary before any logical standard—
iJZed methods of allocating frequencies and powers to broadcasting

S'tations could be evolved.

S. W. Edwards, then Supervisor of the Eighth Radio District
FTith headquarters at Detroit,_had been greatly inte ested in this
INPoblem for some time. It was his contention that the power of
bToadcast stations should not be alloted on the basis of antenna
iIiput but on the basis of millivolts per meter at some predeter-
IAimed distance from the transmitter. With this idea in mind a

file

IIield intensity meter was built in the Detroit office and taken

 

 

-59-

to Washington, D. C., to be calibrated by the Bureau of Standards.
Field intensity measurements were made with this meter on
stations WWJ in Detroit; TTAM, Cleveland; US , Atlanta; and TRC
at Washington. _It was on the WWJ survey that the radial method of
making field intensity surveys was first devised. 0n the strength
of these surveys, Mr. Edwards was able to convince the Division
of the value of surveys of this type and of the necessity for
purchasing aceu‘ate field intensity equipment. Authority was
granted to have the Bell Telephone Laboratories design a portable
field intensity meter suitable for the use of the Division. Ho
specifications were drawn up for this first set but the engineers
of the company collaborated with Kr. chards, who visited the
Laboratories once a week for several months until the meter was
delivered in 1927. A special car body of wood and composite
material was designed to house the equipment. It was necessary
to use a non-metallic body in order that the 100p could be inside
without being shielded. The battery compartments were copper-
lined to shield them from stray fields and special compartments
were furnished for the 100p antennas not being used and for cali-
brating equipment. This special body was equipped with shelves
along the sides for use in computing measurements and also to use
in case it was desired to give commercial Operators examinations.
his body was mounted on a motor car chassis chosen particu-
larly for its easy-riding qualities and dependable operation. A
Packard chassis was purchased for this purpose. This first test

car and meter was tested out by the Detroit office, several sur—

veys being made on stations in this area. The results were so

-40-

mfldsfactory that contracts were given the Western Electric
Cmnmny for two additional field intensity meters and the Packard
Ikmor Company were given a contract for two additional test cars.
One of these cars was assigned to the Atlanta office and one was
assigned to the San Francisco office. Ir. Edwards and Hr. J. E.
Brown of the Detroit office accompanied the latter car and made
several surveys of stations on the west coast. Kr. Edwards re-
turned from this trip more than ever convinced of the feasibility
of the plan of licensing stations y radiated power rather than
by antenna input power. He succeeded in selling the idea to the
Invision to the extent that they authorized three more cars and
field intensity meters.

About this time several engineers were added to the Divi—
sional staff through Civil Service examinations for the purpose
0f handling this new equipment. These men were for the most part
assigned to the Detroit office for training. Hr. Edwards was
Placed in charge of the develOpment and production of cars, field
intensity meters and frequency measuring equipment; the central
frequency measuring station at Grand Island, Nebraska, and all
secondary frequency standard stations being built under his direc-
tion. The author was one of those engineers reporting to the
Detroit office in October, 1928, and took part in numerous surveys
on stations in the Eighth District. The complete data for one of
these surveys is shown in Chapter Five.

As fast as the measuring equipment and cars were finished
aminmn were trained to operate them, they were assigned to the

'Wndcus districts where they were put to the immediate use of

 

 

 

 

-41-

determining the field patterns of the stations in each locality.
Aside from Detroit, Atlanta and San Francisco, cars were assigned
to Chicago, Baltimore and New Orleans. In 1930 two more cars

and meters were purchased and assigned to Boston and to Seattle.
The author and Er. Edwards drove this last car from Detroit to
Seattle via Los Angeles, San Francisco and Portland, at which
places stops were made to install frequency measuring equipment.
A picture of this car and the field intensity meter is shown.
This car was the last of eight purchased and put into commission
by the Radio Division.

Many hundreds of field intensity surveys were made by the
Radio Division with these test cars and meters and they have been
used to a large extent by the Federal Radio Commission in deter-
mining their basis for broadcast station allocation. In July,
1952, the Radio Division of the Department of Commerce was abol-
ished under the provisions contained in Sec. 511 to 514, inclu-
sive, of the Congressional Act, approved June 30, 1932, and en-
titled "An Act making appropriation for the Legislative Branch
of the Government for the fiscal year ending June 50, 1935, and
for other purposes." Under these provisions some of the person-
nel and all of the equipment of the Radio Division were trans-
-ferred to the Federal Radio Commission.

The radio test cars which have been so instrumental in fur-
thering the knowledge of radio wave propagation in the United
States are still located in the original cities to which they
were assigned, but due to the present economic conditions, are

being used but little.

 

-42-

El!"

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”ADIO DIVISION
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A. - .-. .". a. - .. . .-

Field Intensity Meter mounted in Test Car.

 

 

 

 

 

-45-

 

i

 

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i
I ". ' v a. '
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Radio Test Car and Joshua trees near Barstow California.

 

 

 

 

 

Chapter Three'
THEORY AND TYPES OF FIELD INTENSITY’HEASURING EQUIPMENT.

UNIT OF * ELD INTENSITY}

The design of all equipment for measuring field strength is
based upon electro-magnetic theories of wave prOpagation. The
first step in such design is, then, to have a clear conception of
these theories and a definition of an absolute unit of measurement
of the electric field produced by a transmitter at any point in
the space surrounding it.

This unit of measurement may be defined as a unit potential
difference produced in a unit vertical antenna which is perpen-
dicular to an ideal grounded plane, by an advancing electro-mag—
netic wave. The unit of height is one centimeter and the unit of
potential one volt. The unit of field intensity is, therefore,
one volt per centimeter. In this definition, it is assumed that
'the antenna has no effect in changing the field at the point where
'the measurement is taken. In general practise the height is usu-

Eilly'measured in meters and the potential in microvolts. Hence
‘tlus more usual unit of field intensity is the microvolt per meter.
II'l‘iis is usually written.g£, In the C. G. 8. system, this is
equal to 10-8 e.s.u. m
The problem of field intensity measurements in the simplest
analysis is that of measuring the voltage drop produced in an an-
teIina by the electric field and dividing this by the height of
'tfue antenna. However, the height in this case is not the physical

he fight of the antenna but the effective height.

-45-

Each increment of voltage induced in the antenna causes a
flow of current,downward through the receiver to ground. Hence
each increment of antenna has flowing through it in addition to its
induced current, the current which flows in each increment above
it. So the current is greatest in the base of the antenna and
if the voltage across the receiver at this point is divided by
the physical height of the antenna a much smaller value of field
intensity would be found than really exists.

The effective height is defined as that height throughout
which the current flow is the same as at the base, and the vol-
tage across the receiver remains the same as actually measured.

Due to the ratio of size of a 100p antenna to wave lengths
within the broadcast band, the effective current is practically
the same throughout the coil and the effective height depends
only on the constants of the loop. For this reason the loop an—
tenna is most generally used for the measurement of field in-
tensities within this range.

When the plane of the 100p is parallel to the line of prepa-

gxation of the wave, the voltage induced in the 100p is

_e :: aTT-Fu-AHH'IO‘F (1)

1Where e a voltage induced in loop
f . frequency in cycles per second

u . permeability, usually u u 1

area of 100p in square centimeters

N number of turns

H 3 effective value of magnetic field intensity in gausses

-45-
By Faraday's laws, an electric field in motion creates a
magnetic field or vice versa, the relationship between the two

being expressed by

H: 3 (a)

30c:
Replacing the H in equation (1) by its value in equation (2), we

have

e :ZTFfAN—ggo-"O‘? (3)

From the discussion on effective height in a previous para-
graph, we have also
e=eh (4)

From (3) and (4) we find that the effective height of a

I

100p antenna

h: “WA“ (5)

3.‘ol°
and the field intensity measured by a loop antenna at any point

in the space surrounding a transmitter is expressed by the equation

e==f§§fi ‘6’

there e _ voltage induced in the loop by the signal

f : frequency in kilocycles per second
A = area of 100p in square centimeters
N = number of turns

The problem, then, of measuring the field intensity of a
Iwadio field becomes that of correctly measuring the voltage in-
fillced in a 100p antenna, the physical constants of which are
accurately known. This problem has been attacked from different

Erngfles by different manufacturers of field intensity measuring

equipment. 1 brief description of some of this equipment will

follow.
me am ELECTRIC 1386844 EQUIPIILE

I'I ._J‘_) ...J

This type of equipment was developed in the Bell Telephone

Laboratories. It is a modification of an earlier type developed

by Friis and Bruce and res built to meet the requirements of the
Radio Division, U. S. Department of Commerce. Its essential

parts are:

1. Four loop antennas covering frequency ranges from
200 to 6000 kc.

A sensitive superheterodyne receiver.

An attenuating network calibrated in steps of g'db.

2

3

4. A calibrating oscillator.
5

“ system for calibrating the first modulator tube.

As the voltage induced in the loop may be an exceedingly mi-

:nute value, it is necessary to amplify this voltage greatly in

order to raise it to measurable quantities. This raise in gain

Inust be accompanied by very stable operation of the receiver and

iihe gain must be accurately calibrated. A double detection type

Crf receiver lends itself admirably for this purpose. In addition

‘tCD permitting a high gain in the intermediate stage with great
‘S'tability, it has the advantage of allowing the calibrating to be

IDEErformed at a lower frequency than the received signal. In this

1”Tl-Filmer, the accuracy of measurement is independent of the fre-

cinfancy of the received signal and also, capacity effects in the

at‘tenuating network are greatly diminished.

A schematic diagram of the W. E. D. 86844 Test Set is shown

‘111 Fig. 8.

 

 

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-48-

The loop antenna is divided into two sections. From a high
frequency standpoint these are connected in series and tuned by
Condenser Cl.

By the modulation theory, when two frequencies are mixed in
the plate circuit of a detector tube, there are present in the
output the sum and difference of the two frequencies. In the
double detection type of receiver the intermediate stage is tuned
to pass only one fixed difference frequency plus or minus its
audio components. As the received signal may be anywhere within
the range of the set there must be provided in the set an os-
cillator which may be adjusted so that the difference between
its signal and the received one is equal to the fixed frequency
of the intermediate stage. In the case of the Western Electric
set this frequency is 83 kc.

The attenuating network is connected in between the first
detector output and the intermediate stage. The gain of the inter—
Inediate stage is 100 db.

This stage is followed by a second detector in the plate
(Bircuit of which is an ammeter. An audio amplifier is provided
ffiar convenience in listening to the signal during the measuring
13 recess.

A calibrating oscillator is also provided to furnish a known
'anltage for comparison with the received signal. The measuring
fFNPocedure is, roughly, to tune in the signal and adjust the at-
tRainwater so that a convenient value of current is noted on the
Sflacond detector plate meter. The calibrating oscillator is then

tnArmed on and a signal of the same frequency and of known voltage

-49-

is impressed on the first modulator tube. The attenuator is

then adjusted so that there is the same value of current on

the plate of the second detector as when the signal was received.
The calibrating voltage introduced in the 100p is then measured
with the 100p short circuited. The three attenuator readings
resulting from these Operations are used in computing the abso-
lute values of field intensity as will be shown later.

This measuring routine will now be taken up in detail,
pointing out the reasons for, and advantages of the design of
this type of equipment. A problem present in the design of any
field intensity equipment is that of introducing a voltage-into
the 100p in such a manner that conditions are not greatly dif-
ferent from a voltage introduced into the 100p by electro-magnetic
coupling with a radio wave. This has been accomplished in this
set in the following manner:

. Referring to Fig. 8, the calibrating voltage is supplied to
the 100p by the coil Ll, which is coupled to the calibrating 0s—
cillator. One end of the coil is connected to the switch D1 which
(zonnects the 100p to one position called L00p, or to another
(walled Local Oscillator. When it is in the L00p position, the
CCDII is connected between the two sections of the loop and intro-

<itu3es a voltage in series with the 100p circuit. This can be
assumed to have the same effect as the voltage induced in the loop
1337' electro-magnetic coupling provided the tuning capacity is
llizrge as compared with the distributed capacity of the windings.
This has been taken care of by using four 100ps to cover the fre-

QJJGIncy range and by shunting the tuning condensers with large

-50...

fixed capacitances so that even at minimum setting the ratio of
the tuning capacitance to the distributed capacitance is large.

To offset the capacitance to ground from terminal 4 formed
by the grid and filament of the modulator tube, a small variable
condenser Cg is connected from terminal 1 to ground. By this,
the 100p may be balanced so that the voltage at 4 and 1 of the
standing wave set up in the loop by L1 will be equal and 180 de-
grees out of phase with reSpect to ground.

The potential appearing across the grid and filament of the
tube is now that inserted in the center of the loop by Ll multi-
plied by a step up factor due to the impedance of the loop. This
factor is called the L00p step up or Q of the 100p and when the
voltage is measured across the whole loop this factor is denoted
by the expression'QRL. , where R is the resistance of the loop.
In this case where the voltage is measured across half the loop
(the 100p being center-tapped) the 100p step up is equal to‘gL%.
Denoting this expression by B, the voltage on the grid of th:

tube from an incoming signal is

ExzexB ('1)

Where ex is the voltage induced in the 100p by the signal.
The voltage appearing on the grid of the tube due to the vol-

tage introduced by L1 is
V = V B (‘3)

Where v is the introduced voltage.
By a method which will be described later, the first modu-

latOI-tube has been calibrated as a vacuum tube volt meter. For

 

 

 

 

 

-51-

the type of tube used a value of 1.5 volts has been chosen as
the best value to use for V.

The voltage appearing at the input of the attenuator due to
an induced loop voltage eX is

E: EbEme (9)

where Eb is the voltage of the beating oscillator

Km is a modulation constant.
This voltage is, of course, an intermediate frequency one.

The voltage appearing at the input to the intermediate fre-
quency stage when the attenuator has been adjusted so that a

convenient midscale reading is noted on the plate meter of the

second detector is

Km EbEx (Io)

E.=
a.‘

 

Where a1 is the attenuator reading.

In a similar manner the voltage appearing at the input to

tr“? attenuator due to the calibrating voltage V is

5‘; KmEbV (H)

arui_ the voltage appearing at the input to the intermediate fre-
qHalley stage, when the attenuator has been adjusted to give the
saunxa value of second detector plate reading as with the signal
V'Ql‘tage, is expressed by the equation

El = Km EbV (‘2)
a2-

Equating (10) and (12), we have
- .92..
Em-V a; U3)

armi equating (7) and (15), we have

 

 

 

 

 

-52-

6! =%%i ((4)

The switch D1 is now thrown to Local Oscillator position.

In this position the voltage v is impressed across the terminals
1 and 2. As the 100p is still tuned to the frequency of the
local oscillator, the impedance is high across 1 and 2 with re-
spect to L1 and this voltage is reflected on terminals 3 and 4.
This in effect short circuits the 100p and impresses the cali-
brating oscillator voltage across the input of the tube without
disturbing the circuit constants.. The voltage at the input to

the attenuator is then

E“:KmVEb ()5),

and the voltage at the input to the intermediate.stage with the
attenuator adjusted to give the same reading as in the two pre—

vious cases is
E‘; KmVEb 0(0)
(1.3

 

Substituting the value for V given in (8) in equation (12), we haV13

E'ZKMVBEb (V1)
0L2.

Bquating (16) and (17)
B: 0.2. ('3)

0.3

 

Replacing this value of B in equation (14), we have an equa-
tion for the induced voltage in terms of the known calibrating

voltage and the attenuator readings.

(ix =1 \/ 9%:gE3' (V3)

 

 

 

-53-

Now replacing this value of the induced 100p voltage in equa—

tion (6), we have

5 :. 1<_V_. . 4291 (20)
1° “=—
3- to"
Where K : '—'—-‘2-n,AN
V = 105 I
f : frequency in kilocycles per second.
This value K V is a constant for any one frequency and a

f
chart is furnished in which K V is plotted against f. On a sur-
f

vey, then, the process of'measuring and computing the field in-
tensity‘at any one point is a fairly rapid one.

With the 100p antennas, the set is capable of measuring
fielni intensities ranging from 20 microvolts to 900,000 microvolts.
AS ‘brm sensitivity of the set varies with the frequency, these

Vallles may vary. For higher values the 100ps are replaced by

00113 by means of which field intensities up to '7 volts may be

meEisaured- measurements made with the coils are not as accurate

as ‘thcme made with the 100p because the coils are necessarily
nearer to the shielding of the set.
In order to measure any signal, it must of course be compared

W143h1 e.standard. It has been shown how the modulator tube is

usehi. as a vacuum tube voltmeter so that the voltage impressed on
the grid by the signal may be compared to a standard 1.5 volt
e‘rnotf. impressed on the grid by a calibrating oscillator. The
me"thedof'determining this 1.5 volt potential is now described.
Diagrams of the calibrating equipment is shown in Figs. 9

Emmi 10. V8 and V9 are a 1000 cycle oscillator and amplifier,

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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F:IGI £9

 

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-54-

respectively, the output of which is impressed on the grid of V6,
the tube to be calibrated. R1 is a calibrated 500 ohm resistor
in the grid circuit of V6 in series with the output of V9 and

a thermocouple inserted in the socket V7. The plate circuit of

'

V6 is connected through meter L1 which is also in the plate cir-
cuit of V5 the modulator tube. Fig. 10 shows a circuit consisting:
of a 4% volt battery, a decade resistance box, a milliameter, a
D.P.D.T. reversing switch and a patch cord.

The calibrating procedure is as follows: With the 1000 cycle:
oscillator turned off, the patch cord of the battery circuit is
inserted in jack J1. The thermocouple is placed in the socket V7
and the decade resistance is adjusted so that the milliameter MO
shows 3 milliamperes flowing in the circuit through Bland the
thermocouple. The deflection on meter M3 is noted for this con-
dition. The switch D0 is then reversed and the deflection on M5
again recorded. If there is a difference, a series of readings
are taken and the average value used. The battery circuit is
then removed from.Jl.

The modulator tube is removed from socket V3 and placed in
socket V6 and the filament, plate and bias voltages adjusted to
normal Operating values. The 1000 cycle oscillator is now turned
on and by means of the rheostat R2 the current through the thermo-
couple is adjusted until meter H3 indicates the same value as
when 5 milliamperes were flowing through the thermocouple from
the circuit. There is then a 1.5 volt potential at 1000 cycles

impressed on the grid of the modulator tube. The reading on the

meter M1 is recorded. It is now possible in the regular field

-55-

intensity measuring routine to impress 1.5 volts from the cali-
brating oscillator upon the grid of the modulator tube V5 by ad-
justing the coupling of L1 so that the reading of M1 is the same
value as when the tube was in the calibrating circuit. It is alsc>
easy to check the over-all gain of the intermediate stages by
calibrating the second detector also.

In this particular set, the voltage of the beating oscillator.
is coupled to the plate circuit of the modulator tube rather than
the grid as is done in many superheterodyne circuits. This keeps
the grid free from any voltages except those to be compared and
results in a greater accuracy of measurement.

A11 circuits are well filtered and well shielded. The set is;
mounted in a cabinet as shown in Fig. 11. This cabinet is adap-
table for easy mounting in a test car such as that designed by
the Radio Division, Department of Commerce. The various knobs and.
dials by.Which the current may be adjusted are conveniently mountsaci
on both a horizontal and a vertical panel.

Although the modulator tube will usually maintain its cali-
bration for several days, for best results it is best to calibrate
this tube and check the over-all characteristics of the set every
morning before starting on a survey. This calibrating and check-
ing process can usually be accomplished in a ten minute period.

In the course of a survey, the set may be taken over very rough
roads and although great precautions are taken in mounting the set
in the test car, discrepancies may be caused by unusual jolting.
An experienced operator will, however, note any difference in

operation of the set very quickly.

A survey of one station involves only a single frequency, so the

same value of £2 is usually used throughout. However, this value

f
will change somewhat with changes of temperature, humidity and
barometric pressure, so for very precise measurements it is best
to compute this value for each measurement.

Care must be taken that the loop is not affected by near—by

objects. After the station is carefully tuned in, the loop should

be rotated to see if a good minimum is obtained. If not, the set

should be moved to a location where a good minimum is possible.
In.making the measurement, the 100p should of course be oriented
for maximum signal.

One advantageous feature of this set is the addition of meter

balancing potentiometers. With careful operation by trained per-

sonnel, the Western Electric set is capable of an over-all accu-

racy of measurement of 5%.
BEA TMV-ZlA MEASURING EQUIPMENT:

This set is much smaller and is of simpler Operation than the
Twestern Electric D86844, but is probably not quite as accurate.
PTO‘W’ever, it is as portable as a self-calibrating set can perhaps
be Inade and this feature is of great value in making measurements
in, Spots which would be inaccessible to other types of equipment.

This set weighs sixty pounds and may be mounted in a car or
pla<led on a tripod furnished with the equipment. The set is fur-

111shed with two 100p antennas which cover a frequency range of
I‘I‘Om 550-1500 kc. and 1500-4500 kc., respectively. with this
rellgge, measurements of second and third harmonics may be made.

T
hese antennas are mounted in the cover of the cabinet which con-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

RCA TMV 21-A Field Intensity Meter.

r. v

-57-

tains the se . One should be removed, of course, while the other
is being used. The cabinet is of aluminum but the cover is of
wood to avoid shielding of the 100ps. When the cover is lifted
the 100ps are placed in a vertical plane and may be rotated with
the cabinet placed on the swivel tripod.

A circuit diagram of this set is shown in Fig. 12. The prin-
cipal parts are:

1. Two 100p antennas

2. L00p attenuator

3. Calibrating oscillator

4. Oscillator attenuator

5. Sensitive superheterodyne receiver
6. Output meter

The problem is the same here as in all field intensity measu-
ring equipment; namely, that of computing the field intensity in
terms of effective height of antenna and the voltage induced in
the loop by the signal, or E, = -§h—

In this case, the calibrating oscillator is operated with a
low output, thus cutting down on the size of batteries. This cal-
ibrating signal may be adjusted to a known voltage as indicated
on a thermocouple ammeter connected in its output circuit. Between
the meter and receiver input is an attenuator of the mutual in-
ductor type which is calibrated over an attenuation ratio of 10-1.
This attenuator calibrates the receiver over only a part of its
gain control so that it is always necessary to attenuate the vol-
tage induced in the 100p by an amount which brings it within the
voltage range of the oscillator and its attenuator.

This 100p attenuation is accomplished by the insertion of

 

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—58-

calibrated capacitances which give attenuation ratios of l-lO-
100-1000 and 100,000 times.

Thus the voltage at the input of the receiver due to the
transmitted signal can be measured by noting the deflection appear—
ing on the output meter of the receiver and then attenuating a
known voltage of the same frequency until the same deflection ap—
pears. Knowing the voltage at the receiver input and the amount
it has been attenuated, the induced voltage in the 100p can be
computed. Then knowing the constants of the 100p, the field in-
tensity can be computed.

In the system used by R. C. A., the loop step up is not di-

7

rectly measured as in the E. E. system, but is included in the

100p constants. In the term.gLL the only term which is not a

constant for a single frequenc? is R. The resistance of a lOOp

may be affected by objects near the 100ps or by weather conditions.
The measurement of the 100p resistance is a routine part of

a field intensity measurement with RCA equipment. The 100p is

center-tapped and by means of convenient switching arrangements,

a series of calibrated resistances ranging in 3 ohm steps from

3 to 18 ohms can be inserted at the center of the loop. The lo0p

resistance is measured as follows. With the signal prOperly tuned

in, the loop attenuator and receiver gain controls are adjusted

to give a large scale deflection on the output meter. Then by

means of the 100p resistor switch a resistance is interposed in

the 100p center which will cause the meter deflection to drOp to

slightly less than half value. Then the receiver switch is turned

to the calibrating oscillator, which is tuned to the same frequency

-59-

as the transmitted signal, and the mutual inductor attenuator
adjusted to give first, the deflection corresponding to that with—
out a resistance in the 100p, and secondly, the deflection with
the resistance inserted. The 100p resistance is then computed by

the formula

Fez/L‘s: (2')
8—5.
where r : calibrated resistance
8 : attenuator reading without resistance in loop
81 : attenuator reading with resistance in loop

In this case, 81 and S are proportional to the voltages across the
100p terminals with and without the calibrated resistance in the
loop.

The procedure of making the measurement of the induced vol-
tage is the same as the first part of the resistance measurement
and in the usual routine the two can be incorporated into one.

The field intensity is then computed from the formula
6 :pRST {9-2)

where 6 = field intensity in u v
m
T a Loop attenuator reading

Oscillator attenuator reading

U)
ll

LOOp resistance in ohms

raw

a constant depending on loop characteristics and frequency.

In this case the constant

- 2.5.
p—Lwh (13)

 

-50-

where E _ maximum voltage out of mututal inductor attenuator

L inductance of loop

h 2 effective height of 100p
o-2wp ,
Referring to (5), it will be noted that f also appears in
the formula for h.
As f is the only variable occurring in P, a chart is furnished

in which P may be obtained from a curve whose equation is
P _ a. constant
{:2

On first sight, it may seem that the formula 8,: and

1 :rlCD

5;: PRST are not closely related, but closer analysis -hows that

C

all the components of 2 show up in PRST in one form or another.
By this method the 100p step up is taken care of in the computa-
tion and no corrective measurement need by made.

One great difference between the RCA and the U. E. equipment
is that in the former a switch is used in the grid of the modu-
lator tube to connect the receiver to either the calibrating os—
cillator or the loop. It is not usually necessary in either set
to turn the 100p to minimum position when using the calibrating
oscillator except in the case of a very strong signal. In the
RCA set the lo0p is disconnected from the receiver when using the
calibrating system and in the W. E. set the calibrating signal
is usually so much greater than the incoming signal that the ef-
fect is negligible.

The measuring range of the RCA THVBlA is from 20 microvolts

per meter to 3 volts per meter under normal conditions. The sen—

-51-

sitivity varies, however, with frequency and with the condition
cm the batteries. These conditions do not affect the accuracy of
measurement, as the set is self-calibrating.
OTHER TYPES OF MEASURING EQUIPMEET:

The two test sets previously described are the only complete
cmmmmcially'manufactured field intensity measuring equipment on

the market, but there are a great many experimental meters which

nmy vary considerably in some details. The General Radio Company

manufactures a signal generator which is used a great deal in

field intensity measurements with composite sets. This signal

generator consists of a radio frequency oscillator having a range
Of 500 kc. to 1500 kc., a thermocouple ammeter calibrated in mic—
rovolts and a stepped attenuator. A calibrated shunt resistance

is furnished which may be connected across the attenuator, which

reduces the attenuator to one-tenth of its normal resistance and

inserts one ohm in each side of the loop. An audio oscillator

is furnished to modulate the radio frequency oscillator in order

to Kwke comparison tests of modulation. To make field intensity

 

measurements, the following equipment must be added:

1. A balanced 100p antenna.
2. A sensitive receiver, either tuned radio frequency
or SUperheterodyne can be used. The low frequency detector is
used as an uncalibrated vacuum tube voltmeter.
5. A micro-ammeter in the plate circuit of the detector.
4. If modulation tests are desired, an audio amplifier
Withan output plate meter must be provided.

Measurements with this type of equipment consist in inserting

a known e.m.f. at the center of the loop which is the same fre—

 

 

 

 

 

 

 

Y I
L")

quency as the radio field to be measured and which causes the
same deflection on the detector “late meter as the e.m.f. induced
in the loop from this field. In other words, referrinrj‘ leTf‘in to

the formula €= _e_, this method measures e directly-u Ls shorm in

Fig. 13, the output of the signal generator is mafsured in micro—

DETECTOR
SIQHAL. GENERATOR pLATE METER

Regen VER

CALIBRATED DETECTOR
m MICRO —-

ANPLIF‘E'r,

BLOCK DIAGRAM oF GENERAI— gAmo StéflAk GEHERATOR
E19. l3

OUTPUI MEIER

 

Volts on the calibrated thermoammeter and attenuated a known amount.
The greatest loss in accuracy in this method results from the dif-
fieulty in building an attenuator for these hich frequencies. The
General Radio Company claims a maximum error in this attenuator
°f 15%.

Paul B. Taylor has devised an inrenious method of measuring

fleld strength which has considerable merit. In this set the 100p

 

 

-65-

step up is computed from three simple measurements of output vol-

tage without the use of any attenuating network or of a calibrating

voltage inserted at the center of the loop.

The set consists of:

a.
b.
c.
d.

3.

Two 100p antennas

Two sets of four equal calibrated resistors
Two calibrated conductances

vacuum tube voltmeter

Output meter

A diagram of this meter is shown in Fig. 14.

 

1. Loop antenna

2. Signal shorting switch

5. Calibrating resistance R.
4. Calibrating conductance G.
5. Tuning condenser

6. Grid leaks

-54-

One set of resistors and one conductance is used with each
100p. The 100p is center tapped and balanced to ground and all
the radio frequency circuits are also balanced to ground. The
voltmeter consists of two Type 864 tubes with push-pull input and
parallel output. he output meter is a high resistance micro-
ammeter in parallel with the plate circuit.

The vacuum.tube voltmeter must be calibrated beforehand with
audio frequency alternating current. In a mathematical analysis (I)
the design of this set shows that the 100p step up depends not
only on the usual termgLI1 but also on the expression'§1§_ where
C is the tuning capacityRand G is the normal conductanceGin parallel

with the 100p due to condenser dielectric, voltmeter, etc.

He develops a formula showing the 100p step up to be

: v-v v-v ‘. I '
P T VRR . V66 33 {24)

 

Where V the voltage normally measured across the 100p due to

the radio field whose intensity is desired
VB = the voltage measured across the 100p when a known re-
sistance R is inserted in series with the loop

VG the voltage measured across the loop when a known con-

ductance G is paralleled across the 100p.

Most designers assume that a lumped e.m.f. in the center of
'the 100p is the same as a distributed induced e.m.f. provided that
'the tuning capacity is large in prOportion to the distributed

<3apacity of the loop winding. In this set no effort has been made

(1) A compact Radio Field Strength Meter - Paul B. Taylor
I. R. E. proceedings February, 1934.

 

 

-55-

to provide a large minimum capacitance, but this discrepancy has
been taken care of by measuring VF first with two equal center—
tapped resistances inserted at the center of the 100p and then
with two like resistances placed between each end of coil to

ground. The value of YR used is the arithmetical average of these

two me asurement s .

Knowing the gain of the 100p P, the voltage induced in the

loop can be computed from the formula
Te = -!L— (25)

and knowing the induced voltage, the field intensity can be com-
puted by the usual formula
6:5,:-

This set has the advantage of having fewer parts and conse-
quently is more portable than some. It has the disadvantage that
libs sensitivity is low. The range of this set is from.l milli-
VtfiLt to 4 volts. The designer claims an over—all accuracy of

Unnasurement of from 2% to 5$ for this equipment.

 

 

Chapter Four
METHODS OF MAKING FIELD INTENSITY SURVEYS.

Early field intensity measurements consisted mostly of spot
nwasurements at certain distances from the transmitter with a
view of determining an attenuation factor rather than of determin-
ing the shape of the field pattern of any particular station.
Spot measurements of this nature cannot be termed a survey. When
the need for knowing the pattern of the radio field surrounding
a transmitter became apparent, methods were devised for making a
systematic group of measurements or a field intensity survey.
There are three methods which are used, namely:
1. Block method.
2. Circular method.
3. Radial method.
A description of each method and a discussion of the advan-
taSHes and disadvantages of each will be now taken up.
w}: METHOD:
This method consists in blocking out the area surrounding the

treunsmitter into squares of perhaps 1/8 mile sides as Shown in

File. 160..

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

F:I(3.|€H1.

 

 

-57-

In practise city maps are generally used for this type of
survey and measurements are made at street intersections.

Measurements are taken at each corner of the squares and
afler the field has been covered to the required distance from the
transmitter the points of equal intensity are connected by con-
tour lines.

Surveys of this kind are usually used in city areas where

a detailed pattern showing dead spots is required. Such surveys

are of great value in determining the field of police transmitters

A survey of this type necessarily means many-measurements

and.is usually rather slow and expensive. It is also very diffi-

cult to draw contour lines on a survey of this kind because of
tlme fact that it would obviously be impossible to draw contour
liJaes between every point of exactly the same field intensity, as
in-many cases they might differ by only a few microvolts and very
likely there will be only a few points of identically the sam

I'ea'zling. It is necessary, then, to draw lines of average field

intensity.

(gimme METHOD:
In this method the area around the transmitter is divided

irrto circles spaced equal distances apart as shown in Fig. 17a”
These circles are first marked on a topographical map and
1fllen.measurements are made at points appearing on the circles.
This method has the disadvantage that it is not usually
TDOssible to make measurements at equal intervals on the circle,

and much time is wasted driving between points of measurement.

 

 

 

 

-68—

F:|Ge l'lan

This method has the same disadvantage of the block method
in that relatively few measurements are of exactly the same field
intensity and contour lines of average values must be drawn.
RADIAL METHOD:

The method devised by the Radio Division of the U. S. De-
partment of Commerce has the most merit and is now used extensive-
ly. This method has been termed the radial method and as the
name implies, consists in taking progressive measurements in radial
directions from the transmitters.

In making a survey by this method, government topographical
maps of the territory surrounding the transmitter are first ob-
tained if possible, and radii are marked off in at least eight
directions at nearly equal angles, providing that topOgraphical
conditions permit. These are technically referred to as radials
in field intensity work. See Fig. 180.. Measurements are started

as a distance of about two or three wave lengths from the station

-69-

in order to get out of the range of the induction field. Close—
in measurements are made at intervals of about 3/10 of a mile and
this interval is gradually increased until at the point where the
inverse distance curve begins to flatten off measurements are
only necessary at intervals of several miles.

On roads leading in a radial direction from the station, rapid
progress can be made and by comparison of the car speedometer, the
terrain and the topOgraphical map, the points of measurement can
be accurately spotted on the map. In the direction in which no
radial roads run, particular attention must be paid to the terrain
and road intersections. After a few surveys by use of these topo-
graphical survey maps one becomes very proficient in correctly
spotting a measurement point.

As fast as the field data is gathered, it is transferred to
charts which contain, in addition to the measuring data peculiar
to the type of equipment used, the time of measurement, the com-
puted field intensity and the air line distance from the station.
Types of charts convenient to use with Western Electric and RCA
equipment are shown in Chapter Five of this thesis.

From this data, characteristic curves showing field intensity
as ordinates plotted against distance as abcissae are made. A
sample of the usual curve obtained in this way is shown in Fig. 19.
It will be noticed that this is not usually a smooth curve, but
because of shadows local to the place where some of the measure-
ments are taken, there are dips and humps in the curve. A dotted
line is now drawn connecting the peaks of these irregularities.

This dotted line of course eliminates all effects of local shadowing

 

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ii wit tit...~it‘:tti,_;iv l~ ti"“2:;lt.tit"i by (UV tuitut‘ Ui’ 2t. City. WWI),
or pvt-min: nt 1. tion! fmtztrt- within it, and on the margins of
tlu- ma!» :llt' ltlilllt‘tl tho- mung-s of adjoining: quadrangle: of
whiuh main haw lmvn liltitii~ltmi. er 31.11”“ quzulmnglts in
tin» l'nitwl Stair-.4 lmxu- lw-n snrwy-tl. :tlui illillt“ of tlwtn
similnt‘ to the mm on tho otlwr kivlv of this sheet have been
puLl'Jit-tl.

The topugmpitiv map is the lum- on which the gm‘ilogy :md
mine-ml roenuz'u-a' of at quadrangle are rvpttsrntetl, and the
maps showing the-r tllziturt-s are lmttml togetht r with a descrip-
ti‘t’t' tt-it to form :1 full” of tht' (itulogit' Atlas of the United
Ht Hm. \lorv than 2‘30 folio» have been published.
. ltnlvi map-z oft-:u-h Stat-1 and ot‘ Almku tlllti llawnii showing
tlu- tilt':t~ «on mi lty tttlttt;;1:l}'loit' math uml gvuloé-ic folios pub-
l|~lml lav the I'nitml Hun-s timriogiml Survey may he obtained
flu-t. ( 'opiw ol' t‘w ~I;m«l:ml lulu-gittltllit‘1”:th um} he obtained
ii)!‘ In mum» var-h; Ntlllt" ~pt-ci:t| map- ttl‘i‘ <ol.l :tt (title-rent prices.
.\ cliu-ount of l” per want is allowed on an order for maps
amounting: to $3 or more at the retail price. The geologic
l'olius :m- «M for 23."; units or more (‘ilt‘iL the price depending
on tlu- <i/.v of the folio. A circular describing: the folios will
lw win on rwlttmt.

Alli-limitions ii-r mat-u or tiilios should lie accompanied by
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‘ofi‘

-70_

and shows the general trend of the wave. One of these curves is
made for each radial.

From these dotted lines even values of field intensity are
taken and spotted on the radials at the distance shown on the
curves. The contour lines are then easily drawn through the cor—
responding points on each radial. Although this method has been
objected to by some on the ground that it does not indicate local
shadows, it has already been pointed out that contours made by
other methods are usually averaged results and therefore no more
accurate. The radial method is by far the quickest and easiest
way to show the general field pattern laid down by a radio trans—
mitter.

It is possible to show shadows by this method by investigating
areas where irregularities occur a little more thoroughly. Shad-
ows which persist to great distances will of course appear in the
final contours. In cases where the survey is carried out to low
values of field intensity, it may be necessary to fill in shorter
radials at the outer edge of the survey. In this latter case i
where the field intensities may range from above a hundred thousand
microvolts per meter for measurements close in to the station to
values below one hundred microvolts at the far points of the sur-
vey, it is convenient to use logarithmic paper on which to plot
the radials. This method is especially adaptable for showing at-
tenuation along each radial. Examples of the use of IOgarithmic
paper are shown in Chapter Five.

In all cases, regardless of the method used, the field force

must have the close cooperation of the station personnel in

keeping the output of the transmitter constant at all times

during the period when measurements are being taken.

 

 

Chapter Five

EYlHPLES OF FIELD INTENSITY SURVEYS.

SURVEY OF XXL-"Ii - ROCill'vIS'I'ZERg1 N. Y.:

 

In January, 1930, the author and Er. F. E. Kratokvil, both
employed in the Detroit office of the Eighth Radio District,
received orders to proceed with a radio test car to Rochester,
N. Y., to make a field intensity survey of TEAM radio station of
the Stromberg Carlson Co. of that city. The survey was made
with a Western Electric #D 86844 Test Set such as described in
Chapter Three.

WHAM was at that time a 5 kilowatt station operating on a
frequency of 1150 kc. It was located near Victor, New York,
about 12 miles southeast of Rochester. The transmitter was a
Yestern Electric 5 c. The transmitter and antenna were located
on a high rounded hill (see picture). The soil was rather dry
here and in order to get a good ground system the entire hill
tOp was covered by a network of copper wires buried about 1%
feet underground. The antenna was a vertical cage supported by
a cable hung between two 225-foot towers.

Topographical maps were secured for the region surrounding
the transmitter and by comparison of these and more modern road
maps, nine radials were chosen along which to make measurements.
Geological Survey flaps are of especially great value in making
surveys in the eastern part of the United States because most

of the landmarks still stand.

-73-

The weather was cold and most side roads were frozen and
rough, but passable. The condition of roads in always a great
factor in choosing radials when making surveys with the Govern—
ment test cars for they weigh around 7000 lbs. with all equip—
ment aboard and it was a serious matter if one was mired in a
muddy crossroad.

The procedure was for one man to drive and compute the re—
sults of measurements, while the other did the measuring, and to
change work from day to day. The survey was xtended out to
below the three millivolt level. It will be noted that this
level was much higher than that appearing in later surveys. .The
reason for this is that at this time it was considered that a
five millivolt field was necessary for good reception. This
figure has been much reduced at the present time, due to in-
creased knowledge of field intensities, to improved receiver de-
sign, and to increased percentage of modulation.

The set was calibrated each morning and a check measure—
ment was made at an identical point before starting the day's
work in order to be sure that the set was in good condition.

The station personnel COOperated during the survey by keeping
the transmitter conditions constant.

The data gathered on this survey was plotted on cross sec—
tion paper and the usual field intensity vs. distance curves
were drawn. These are shown in Figs. 17 to 25, inclusive. The
terrain in this section of the country is very rolling and hilly
and this condition naturally produces many local shadows along

the radials. In order to show the general pattern of the field,

-74-

these local shadows were eliminated by drawinq dotted lines
connecting the high points of the curve as explained in Chapter
Four.

From these dotted lines, even values of field intens'ty
were taken and plotted on Map #26 showing the roads along which
the radial measurements were aken. Contours were drawn con-
necting the corresponding points along each radial. It will be
noted that the field has an elongated pattern in the plane con-
necting the two antenna towers.

An examination of this pattern immediately aroused suspicion
that the antenna towers were radiating energy. These towers
are approximately 1/4 wave length high and 1/4 wave length from
the antenna, and under proper conditions each might act as a
reflector, thus producing the elongated field. It was decided
to prolong the survey to investigate the effect of detuning the
towers. This was accomplished in a very simple manner by Kr.

Long, engineer of he station. The cable supporting the vertical

(J

D

cage was, during the original survey, insulated close in to t-!
towers and again at intervals along its length. The insulators
were now shorted out, thus increasing the natural period of the
towers by several meters.

A short survey was now taken which included measurements
on all radials at the same close—in points at which measurements
on the original survey were taken. The results of this survey
are shown in Fig. 27. It will be noticed that the elongated pat—
tern has changed to a more circular one. Although lack of time

prevented a more complete test of this detuning effect, the fact

-75-

that the close-in contours were more circular proved conclu-
sively that the towers were the cause of the distorted field of
the original survey. This test emphasizes the value of a field
intensity survey. -

In radial #9, the effect of large buildings and concentra-
tion of wires in the business district of a large city are
clearly shown. The general attenuation in the area surrounding
the station appears to be about the average for the United States.
As a rule, the attenuation along the shores of a large body of
water such as Lake Ontario is much less than for territory in-
land several miles, and the field pattern in most cases will ex-
tend up the shore to great distances. Due to the directional
pattern caused by the radiating towers, this is not apparent in

this case.

 

 

 

 

Antenna towers and transmitter building WHAM - January 21, 1930.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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so.m r commm” mom. oommH“ «am we pamH ca name ocH mmw Hmua
. a . 11 . ”9% 80M“ _
ww.¢ ooomow mme oooom_ coma .fiao. omen mmouo so dmw omuma
Hm.m I ooomsuI momI‘ cooom. mmaH mmmIaouu H5 m. mmm Hmnmec
_ . _ zuoueamo can .
om.m oomecw mom ocoom ocom mousse scam smouon mmm mHamH
m . I» mmxIaoum He 0. m .Mmmao
mH.m comma mom commHII ommH HHmEm um>o mmoHuo so H co. .mIs
Am.m I oomHor Jme oooom ommm omm.eopo He a. on wIImmewe
mm.m coommwm mom. oommmx cmmm .cmou oHIw em om om. .HH.
Hemp moo choo.xcm HoIm commHH mmm oommH ommH om. song He c. mm. mmuHH
. . omen mmouo scan as mm.
wosoa.xsm mm.m oocomH mmm oommHfl ommH mm mm% mega Ha m. m emuHH
mm.m oooeHH mom oommH_ ooom song. He m. cm. omnHHf
pm.H oconH mom oommH ommm amw ecu“ mas mHuHH
i nmwn Souk.
Imm.H ooommm mom oommH ommm Ho m. smog mmouo «mm oHuHH
mm.H ocommm mom oomsH chem mason cone amouom smog
I I no mm soua.Hs mu mm «onHHr
mHIH ooosmH mom oommH omHn coHpmpm oo opsom mm omuoH
.omou mmouo
aseHoHe cccc mm. oooon mom ccmsHh ommm .mpm co Room .Hamm. wmm momucH
mxmezmm mmmHa m . m< m4 _ H4 ona<coq maHa
.ommH .mm .amo moo. IIIcofipmuosHmo soachooa
mason «aaaaomuHm .mmam m.oH u H
.ox omHH u u m a HuHonm ammo. M\>x

same 235% Has: :3.

-79-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

IIIm a II
mm.mH omsm mum oommH m.om umoo_eouu umHHs cmm mamas _
. m mew song a

mmwwm cmwm mom oommH. e.me .mrs H o amp no E? 23 _

ImH ommm mom oommH H mm x eased sous .Hz m m mocha

equ omHm mmm oommH an mmmIEOuu .Hz m s mmHum
mIMH omsm mom oomsH mmH mea sou“ .Hs H m amm«m _
mquHI comm mam comsH mmH .mm scan as mm. me mmeum .
mafia, cmmm momw oomsH mmH mm macaw HmIm. «a mommm.a
mmqu oommH mom ocmsm, mmH m scan .Ha on. n mmmsm _

oqmm oomHH can oommH com H echo .aa m we ooHum

.mcmouuuoua

mH.m oommH Immm oommH, mmm .mqm cmmysouu s. Hma mooum

II, smum IpwomH mom ocmsH mHm ommc omen macho cam ammuH

mmmsam mafia m 2 m Hm 28308 as?
mso.IIooHpmapHHmo gopmHoeos
.cmmH mm.nmw npzomnzoweoouwn mass m.oa u H.aa<
.oa cmHH u u m a Hmflomm ammo. u M\>s

Mm>mbm WBHmzuBmH QAmHm 24EB

 

 

 

 

  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

mH.mH ommm mmd oowom e.mm mmuHs scam .oon cHon demo bb% oaun
c.mH comm one commm mwmm .ccH mom mmaHs co chHc cH mom ccum
e.mH chm mmm commm m.mm camp soHHms ammo mmcu mch m . cmnm
mm.mH comm mum ccmcm cHH ammo: mpHms axon mmmmImmHm m maum
qumH comm cmm commm ch mmcst.ao mam Scum .Ha m H m mmum .
mImH cmHm cmm ccmHm pmH mason Hocnom axon mmcu mmHm m cmsm u
c.me cmcs cmm cccmm mmH mHmHm oH smammHm “cc H mmum
n«MH comm hem ccHHm cmH cmm scum mHHa m. chHc aH c cHum
m.HH oommH pee ccmHm mmm dump ca ammo cum» cams :H c cHum
m 2 cmmm cma commm mmH $5.3 Ha H.H umcmmfiams 5. m scum
mIc ccamHI «em ccsHm mmm mom.aoum mHHe m. mHmHm qH p mmuH
wqc ccmMm «mm ocsHm mmm m. scum .Ha s. macs mch m cmuH ,
mmIm ccmsH cmm ccsHm mam m scum mHHs m mHch :H m mme
ms.p ccmmm omm ccmmm mmm mm scum mHHa uHmm m cmuH
«was ocwmm mHe ccccm cmm mmm.acum mwma uwmm m mmuH
IIMmIm ccmHm mmm ccmcm com H acne .Ha m smaomHn quz m HmuH
mmIm compo cmm commm mco cm acne «HHaymaHMIHmpmuw H mmuH
. mum
Hm.m comma mmm ccmmm cmc cognac qH smegmHa ona mac c cmaH
mmquIIcame cmm commm comm mmmwaouc mHHa m chchH mm _ chH
qum ccmmcH «mm ccmcm cccH pm sou“ mHHa m can» chem aH m mcuwlm
mauII ccchw mHe ccccm omcm nopoHc puma HHHa ummHo m4 om ccuH
cIMIJIqqmmmH mam ccmmm cmmm mmmwaouu «Ha m omen meHm no mm mmcumH
uDHOH> cH
cm.m cccmmH wee commm cccm cognac amHumaspmmum mnanmm mmm mmuHH
howOH>
m.m cccmmH was commm cmmm aH canon omHmmp ch spasm cm cmuHH
.Imqu cccpmm cmm ccmmm cmom camp noon mumsyaumu cH mm mmuHH
- hmanwfim nausea
Immc. ccomcm one cmucm cosmI mam mwm no :oHeommmmanH mm anuHH
«c4 cccmmm «mm ccHHm oommH ass: no game aHmomnac H «cmeHm
ImcHH: A. m as m4 H4 chamccq “aaHa
cmuH.mm .nmu mac. cchmupHHmc nopchmcs
«new Hosanna amen «.3 H H
8. 83 My mum HmHmum ammo. H {EH

 

HHEMDm HHHmZMHZH QHMHhmmde

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

c.¢ cosmH mam ccm.mm mmm .mnmchooom .mma song .Hs s.H am» am mHum
oPHSO m Song

m.m oommH msa ccm.mm mHm .Hs a .sma song .Hs m.H mmm am cHum

s.m ccmsH sea cc¢.mm csm .mmch_c cc .mma song .Hs H.H smm 2m «cum
.omwo: BOHHmh

mm.s cmmmH _ cse ccm.mm mmm Hmmz .mma scum .ms m.H mm% mm cmum
. .noceomz use:

H.c ccmcH mam ccs.mm mHm mpmco no .mm% song .Hs m.m mm% mm mmum
. .momOHmmono.aonu

m.cH cscm mam ccc.mm mcH .Hs m. .mm%.sona .Hs m.m mmm 2m caum
.omson MoHHn

m.mH comm mme ccm.cm am can pmmz .mma acne .Hs m.m mmm am caum
_ .omson

m“ m.¢H csmm mam ccm.mm m.mm opHcs nmmz .Hmm sop“ .Hs m mm» mm Hmum

c.mH mmcH mam ccc.mm Hm .cm%_s°na .Hs m.m Hmm 2m cmum

m.mH cmHH ham coc.mm mm rmasooHcooom .cs%_aonc .Hs m.m cmm .sm scum

.Hanmo owhwm memmoho II

m.Hm cmcH cmm ccm.mm H.Hm mmom .mmom_acnu .Hs m. as» am cone
.mnmwm ochpso

m.mm cmc see com.Hm m.mH .Hmamc mmnmm song .Ha m. mew 2m mmum

mmHHs s m4 m4 H4 cheqccH msHe

I‘ i

 

 

 

.oan .nm hnmsnmh pmmm hp pmmmspnoz “:OHpcman monoaam m.mH u H

.om cmHH . a ma HmHmmm ammo. . H\>M

MmbmbmthHmZHBZH QAMHhrfiflmB

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

m.m cccqs smm ccH.Hm cmH .mmocm cm mcmcnmmcsc some .Hs m. mch an mmnm
m.m cocaw. sea cmqum _ ccH .mmsom pm .mcHa aonc .Hs m. «ch 2m cmum
c.m cmm.m mam ccm.mm mmH mcHa scam .Hs m. .mcmopmmonc pm mcHw 2m mmum
iImas Iccm.m saw cos.Hm mow .Hcccom ammo mmmcnmmcnc #4 mchme sHuw H
m.s ccm.m mam cc¢.mm msH .ccHw song .ccm HcH* 2m mHum
.cmezm cachmmono
m.m cmc.HH mam ccc.mm smm song .Hs H. .cc%_acna .Hs m. ccH* am ccum
c.m cmm.mH cmm cce.mm mmm .mca acnc .Hs m. cow mm mm.»
H.m ccm.mm mmm ccc.mH mmm .scm saga .Hs c. mom 2m mmum
m.m common man ccc.mH mam .mpmssnma cH .mca scam .Hs s. so% am mmum
m.m ccm.cm ch com.cH Hmm .mca Sosa .Hs m. cm» .2m cmum
. c.m ccH.cm mmm ccc.mH mob .ncmoms pH mcmonmmonc mca : ccumH
.enHH hpnuou
m.m . cos.Hm mmm com.sH mmm Scum .Hs m. .mc% sons .Hs m. aca 24 mauHH
.moHH spnsoc.scnc .Hs m.H
ms.H com.ms cmm com.mm cmmH mom scam .Hs m. .mcmosmmono #4 no» .24 mcuHH
How
cc.H ccc.cmH ewe ccH.Hm cmmm acna .Hs m. .mcmosmmoso pm mom :4 ccuHH
mm. ccc.mmm mam cos.mm chm mHamccOHImmmcnmmonc.sona .Hs H. How _am mmucH
.GOHumpm
mm. ccc.mcm Hcm cc¢.mm mch we pmmm .mmmcmHHmn cmmscmm cow :4 mwucH
mmHHs a m4 m4 H4 ZcHemccH msHa
.cmcH .mm succumb umma “:oHpomnHo monogam m.mH a H
.om cmHH u H mm Hchmm ammo. . u\>M

MH>mDm NBHWZHBZH QAflHh 24m?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

.Nmbmbm.MBHmZMBZH QHHHM.2<mB

c.mH csm.m cmm com.mm m.mm .mHH%.sona .Hs c.H mHHm 2m mmum
c.mH cmm.m sea ccH.Hm mm .mmcoo ac scam .mmmommmono cm mHHa 2m mHum
m.mH ch.m cmm cc¢.mm m.mm .cHH%_acnu .Hz ms. HHHm 2m cHum
m.mH cmc.m smw com.mm m.mm .mcHa scum .Hs c.H cHHa 2m mcum
hnpmscsH
m.mH cms.m smm oms.Hm ms oH .mcHa song .Hs mH.H ccHa am ccum
m.mH com.m mmm ccH.Hm mcH .scH%_aopa .Ha H.H mcHa am mmum
m.HH com.s mmm ccm.mH mmH .mmmcpmmonc scam .Hs H. scHa 2m mmum
cucH com.s cmm com.mm cmH mmmopmmonc song .Hs m. mcHa 2m ceum
mmHHs m mm mm Hm ZcHeHccH msHe
.onoH..¢m hnmsnmh 9mm; "nOHpompHQ manages m.mH I H

 

-84-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Mmbmbm.NBHmZHBZH QHHHhufide

 

c.mm cmo.m mcm ccm.mH cm .pHc Hmpmnm nmmz mmHm 2m mmum
m.em cms.a mmm ccc.cm mm cmop cH > pm scam .Hs m. mmHa 2m mHnm
.chmncho mHmmm
m.mm cmm.m sme ccm.cm cm nmmz .mmmonmmcso_scaa .H: m. emHm am cHum
m.mm cccqm cma ccchm mm .mcmogmmoao acne .Hs H. mme :m mcum
mm.mm cos.m cme ccm.cm m.cm .chHc cH cmcn ago .smam .Hs H mmHa am mmum
s.Hm ccmqs cHe cos.mH smH .chHm cH .c¢H%_sonc .Hs m. HwHa am coum
H.Hm cmm.c mom ,ccm.mH cmH .smsm .Ha m. snmcmamc oH cmH%
.mmfio: BOHHoh
s.cm cmc.s cHa ccm.cm HmH mmmz .mmH% sons .Hs m. cmHm
m.cm ccmqm mmm ccm.mH mmH .smHa saga .Hs m. mme
m.mH com.s mmm com.cm mmH .ccH momopmmcsc song .Hs H. smHa
m.mH cmw.HH cmm ccm.mH ccH .mme sch“ .Hs m. mme
.onpmcoq
m.mH cos.c mmm ccm.cm mmH HmmmH .mmHm scum .Hs m. mmHm
mm.sH cos.c mmm cmm.om mmH .mmHa song .Ha H mmHm
mm.mH cmm.mH mma ccm.cm mam .mmHm Sosa .Hs H.H mmwm
mm.mH ccm.mH «ma ccH.Hm mam .mcmonmmosc .HmHm song .Hz m. mmHa
c.mH ccc.sH mHm ccc.cm mmm .cmHm song .Hs c.H HmHmw
mm.mH ccchH com ccmqu smm mmcm cm» mom who .Ha H cme
mmHHs m m4 m4 Hm ZcHemccH msHe
.uuuuuu%uuuunuuuuruuunuuruuuuInuuwuuuuuuuunuuuuuuuuuuuuuuuquI IIIunuuuunrunuuuuu
oan .mm Humwnmh ammoApsom “nOHpoonHm mahogam m.mH I H
.cm cmHH u 9 mm HmHmmm ammo. . axpm

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

m.mH ccm.Hm mmm ccm.cm mom mmccm mamH cc cmHa

cc.HH ccm.mm mmm ccm.cm. mce .smHa Scam .Ha m. mmHa
.mcmon

m.cH cms.sm mmm ccm.cm Hmm Immcao no .mmH%_soaa .Hs s. smHa

m.m cmm.Hm emm cos.cm cHa .mmmnc mama .mmHa acme .Hs m. mmHa

H.c ccm.sm ema com.cm mHm .mmHa song .Ha s. mmHm
.mmHa

m.m ccm.mm mom ccm.cm mmm scum .H2 5. .mcmmmmmonc pm amH%

ms.s ccm.mm cme ccH.Hm mas .mmHa son“ .Hs c. mme

c.s com.mm mam com.sH cmc .HmHa scum .Hs m. mmHa

mm.m ccc.mm mmm coH.cm mmc .cmHa soap .Ha mm. HmHa

cc.m com.Hm mme ccm.cm weo .cHHa scam .Hs s. .cmHa

w ce.m ccm.cs on com.cHd cmmH .mHHa song .Hs mm. mHHa

_ c.m ccc.mm cmm ccm.om cmmH .mmccm mpHos song .Hs a. mHHa

cm.m ccc.sm mmm ccm.cm cmmH .mHHa scum .Hs m. sHHm

cm.¢ ccc.scH cHa com.cH mmmH .mHH%.scna .Hs m. mHHa

cc.m com.mcH mmm ccc.Hm comm .mHHm scam .Hs m. mHHa
Mocha .m .m

cm.m ccc.omH mom ccc.cH csmm song .Hs m. cmcn mch no .mHHa

mmHHs a mm mm H4 ZcHaaccH msHa
oan .mN hhwdflwh pmwmnpdom “noHpomHHQ mmhmgfid m.mH I H
.cs cmHH . c mm HmHmmm ammo. - H\>M

wm>mbm.MBHmZMBZH QAEHMUE¢NE

-86-

 

 

 

 

 

 

 

 

 

 

 

 

.zphoc .H2 0 .mpesoc Hmmz
m.mm com.e ace coc.Hm em .maHommy pmmH song .Hs m cmHm am cHuw
. .coHpmoOH HmmcH
m.mm cmm.m smm cc¢.mH em .cmop mmHm cc .mccHHmm mmmz caH% am mmum
m.mm cc¢.m mom ccm.mH mm .mmmcnmmcho pm .amam .Hs H mmHa 2m mmum
m.mm cmc.m mHe ccc.cm m.ms .mmmonmmono we .smsm .Hs H smHm am mmum
mmHHa a mm me He ZoHaaccH mEHWL

 

 

 

.cmcH .mm samscms

.oM omHH u H

vmwmnvaom “coHpooan

mm HmHmmm

EPmbm :HmZmBZH QHMHnH Edna

mmhmgam m.mH u H

ammo. u a\>m

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

.MomHP

cm.m com.m mmm ccm.sH . mmH .m .m cc cxmo .mHmHu ammo nH mmHa am mmumH

m.s cmm.mH «mm ccm.cm smm .mmHm sons .Hs.m. mmHm 24 HmuHH

.mHoHu oH
m.m cos.mH mmm ccc.cm mmm .cm omen ago .smam .H: m. amHm ad mmuHa
m.m cmH.mH emm ccH.Hm mmm .smzm .Hs m. .cmcn mmHm no mmHa am cmnH
.amdhaw

mm.m com.Hm Hem ccH.Hm cHa cs pxmc .HmHm saga .Hs mm. mmHm am mmuH¢

H.m ccm.mm «mm ccHaHm Hcm .cmop mac .cm .momcsmmcso co Hme 24 cmnH

ms.e com.mm mme ccH.Hm Hcm .mcmcpmmcnc scam .Hs m. cmHa so mHuHH

H.¢ com.em mmm ccm.cm cmm immacc mpHos 0» pace .cmcp who cmHm 2m ccuH

com.cm mmm cce.mm Hmm .smHa mm msmm mme 24 mcuH

. Immel

mm.m ccs.sm msa ccm.mm mmm scam .Hs mm. mH mpscm cc smHm s< manH

mm H.m ccc.sm mom ccc.cm mob .omop cc mmHm as cmncH
_ mm.m cos.Hm sea ccH.Hm mos .mcmosmmopc pm mmHa am meucH

.mHmHa

mm.m ccm.mm mmm cmm.cm cmcH cH memosmmoco_sonc .Hs m. mmHa as mmuc

m.H ccc.cs mme ccH.Hm ccmH .mcmosmmono pm mmHa am cmucm

mH.H com.mmH cmm ccm.mm cmmm .mmmcnmmopc song .Hs m. mmHm Ham cmucH

.mc cmmspmo HHHc 02

mm. ccc.Hmm mam .ccs.mm cams .aoHpmpm mo am momonmmcuc pH HmHa am «Huc¢

mmHHs a mm mm Hm ZcHemccH msHa
Inf
oan .cm hnwfinmh pmebzpsom "GOHpoehHQ manages m.mH I H
.ox cmHH u a 5* HmHomm mmmc. n M\>M

MHPmDm MBHmZHBZH QAMHhuzflmB

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

m.mH ch.m mcm com.sH mm song .Hs H cmomHMWWMmmw ssHa .sm mmmm
mH.mH com.m mcm com.sH mm cmcnmmcno pmmz msHa am cmum
m.eH cmm.m mom com.sH mm mmcs mmHm acc msHa am mmum.
m.mH ccm.m mom com.sH H.¢m omcnmmcno mm asHa am mHum
c.mH cmm.m mom com.sH m.cs scam .Hs m.H omen mch cc msHm 2m cHum
m.mH cmc.m mom com.sH mcH scam .Hs H cmcpmmcpo pm msHa 2m cmuH
w m.HH cmm.s mom com.mH mHH csH% saga .Hs m.H HsHa 2m meuH
_ chmhnonzao
m.cH csm.c mom ccm.sH HaH oH .cmHm Scum .Hs m.H csHa am smuH
c.cH cmm.cH mom ccm.mH mmH scam .Hs mm. mmmcnmmOHmew cmHm am mmnH
mm.c ccH.mH mom ccm.sH mmH mmmopmmcho song .Hs m. mmH% am cm“ H
mm.c com.c smm ccm.sH mcH mmHm eon“ .Hs m. smHa am mHuH
m.m cmm.s mom com.sH mHH mmH%_scma .Hs m. mmHa mm man
mmHHa a ma m4 H4 2cHemccH msHa
. uHHflflHHHflflWflflflflflhflflflflflflflflflflflflflflflfluuHHuHHHHHHHHHuflflflflflflflflflflflflflfllflllllflm IHi
oan .bm Hamsnmh pmesnpdom usoHpoeHHQ manages m.mH I H
.c& omHH n H 5% Hchmm ammo. n H\>M

Mrmfiwmbm WBHWZEBZH

SHE h ESE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

m.s cmm.c mom com.mH smH .pmmc mmHHs .cmcp mch :c moHa am mmuHH
.mmfio: BOHHeh use:
m.m cmH.mH mom ccm.mH Hmm cmcs 2c .HcHxx spa .5 m. mch 5 SLHH
H.m com.HH com com.mH mmH .Hmm: $ch .ccHa scan. .32 m. HcHa am ELHH
23m 893 can oommH 3m .cmcnmmcso sob .aH mm. 8le E. cmuHH
.eGHH Hosom HwIech Henge
mom 8ch mm ccc.mH Em .E 2. .mmHm s98 .E m. cmH* 5 mmuHH
esHH Meson we mch man
maze ccc.cm cmm ccc§H cmm .E 2. .smHiiHK sch Hz a. mme 5 mmuHH
mHé com.m_m com com.mH mmm moon mow scam .E H. 5% H2 mHuHH
m.m ccm.mm ch com.cH cam .cmcsmmono sob .E H. mmH» 2H mcuHH
.HmmfimHHH Emma
_ «m.m ccm.mm mmm ccm.mH mom to mmHa sot .Hs mmH mme 24 mmucH
% ecH cchm cmm comJH mmm .cmca cc .mmHaH s8.“ 3% m. mme 3 $13
_ cc.H com.Hc smm ccc.mH cmmH mmHa sob H: mm. mmHm H2 mmucH
mH.H cccmmH com ccm.mH comm HmHam sob .Hs m. mmle 5 mmucH
mmc. ccc.csH mmm cchH cmmm 8% aces .Hs mm. 8% c2 mHucH
mmc. ccc.HmH mmm cchH cmcm 3% 59G H: mm. cmH% :4 mic
Macho seen much
mos. . ccc.mcH mHm ccm.mH comm 0on no .msHm son.“ .5 m. csHm am mwuc
mm. cchS ch ccm.mH coma. omom 5...: no msHm EH mmnc
3:: a ma mm H4 5338 EH:
oan .mm bnmasmh ammonpnoz unOHpooHHn monogaw m.cH I H
.3. on: - . a ass as. . SH

MMPMDW.WEHmZHBZH QHHHhfiaflmB

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

.aoHnmE
mm.mH cmo.m cmm ccc.sH me go coca .cnoamonooc oH mom» “2m cmum
e.mH cms.m cmm com.sH om .ooon no moono.aona .ccm mom» am mmum
m.mH cmm.m mmm com.mH mm moonmmouc song .Hs m. coon oc comm am mHum
. . .pamH op
mm.mH cmm m «mm com mH as cocoa opmHm .moonmmonc pm mcmfi .2m mmuH
. .pcoH op .cmH
s.HH cms.m mmm com sH ms omcoo soHHoH .mmosmoonc am Hcma .2m oHuH
.eh 0p .oon mesonHoonom.cm0H
H.HH ccm.s mmm ccm.mH cmH Immonc ammo .oHHHpsoHom p4 coma 2m mHuH
_ . .oHoHo
MW mm.cH cmH.c ace coo cH mmH oH coonooopc.sonu .Hs ms. coHa tam mcuH
_ . .oHoHa
mm.c cmm m ch ccm.oH smH oH omoHHHmm some .Hs a. moH% am cmumH
.soceomz sH Hm
mm.m cmo.HH ch ccmuoH com -ooo omymo oH muooH o» pxoz bch use moumH
.mmdon opHgB
m¢.m cmc.mH «mm ccm.mH mHm op ammo .smsomHo ona mac mcH» sa.mcumH
oHlo
mm.s ccm.mH mom ccc.mH mHm coco oH moosmmoao nooz moHa am chmH
omHHs a ma mm Ha chsaccH msHe
cmcH .mm.shocomo .ammoopnoz ”ooHpooan monogam m.mH I H
.om cmHH u a mm HmHmmm vmmo. I %\E

NEmDm. NBHWZHBZH Q‘HMHLH 23E

 

-91-

.noxmp mH ewmnm>m .mwanmmn

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

08mm pm $4 no .md .H« new Macao mhmnasn cap mamas “mpoz
.mahmh MomHoM.
m.m cms.mm .msm com.mm Hcm .sHma scam -oo>nso- .Hs H.H mHmm as mH-HH
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Hmbmbm MEHmZflBZH.QAHHhWE<mB

 

 

FIELD INTENSITY MEASUREMENTS ON WHAM

TESTS SHOWING EFFECT OF DETUNING TOUERS

 

BEFORE CHANGE
16.2 amps.

AFTER CHANGE

ANTENNA CURRENT 12 amps.

 

 

FIELD STRENGTH uv
m"

 

RADIAL NO. LOCATIOB KO. MILES LEFORE CHANGE AFTER CHANGE

 

 

 

 

 

 

 

 

1(North) 1 .85 150000 427000
2 1.2 55400 175000
__p 5 1.0 47200 145000
2(South) 1 .59 210000 427000
2 1.15 157000 207000

5 1.55 252000 157500 .
4 1.55 254000 124500
-3(East) 1 .54 545000 550000
2 .99 505000 424000
5 1.48 227000 188000
4 2.2 155000 180000
5(West) 1 .55 405000 1155000
2* .55 255000 492000
5 1.00 150000 .250000
4 1.75 75200 155000
6(South East) 1 3.5 140000 98000
2 5.9 117000 27000
7(South West) 1 .75 551000 794000
2 1.15 155000 245000
5 1.5 79000 115500
8(North East) 1 .44 477000 1020000
2 .75 192000 595000
5 .94 179000 515000
4 1.15 :;57000 572000
9(North West) 1 .45 1040000 754000
2 .59 550000 575000
5 1.09 255000 175000
4 1.19 500000 202000

 

17.

FIG.

 

 

 

 

MILES FROM STATION

0.503422 r: 42.5.3.2... 040....

 

 

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DISTANCE IN MlLES

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-95...

OUTLINE OF A COMMERCIAL SUPVEY}

In order to be of the fullest value to a commercial station,
a field intensity survey must include an analysis of the data
obtained with measuring equipment. Hethods of making a survey
and of tabulating and graphically interpreting the data from a
purely engineering standpoint have been previously shown.

Owners of a station Operating for commercial purposes must,
however, know more than this. In order to interest manufacturers
and retailers in using that particular station to advertise their
products, the owners must be able to lay before the prospective
advertisers data showing the potential possibilities of the sta-
tion.

These potential possibilities must include engineering, sta-
tistical and psychological data. The information secured under
engineering must be subdivided into primary and secondary cover-
age. The terms primary and secondary coverage have been coined
by Jansky and Bailey, and according to them primary coverage may
be defined as the area Within which a station may be received
satisfactorily at any time of day or night. Secondary coverage
may be defined as that area within which a station may be received
satisfactorily only a portion of the 24-hour period. The term
satisfactory service cannot be arbitrarily defined upon the basis
of a certain minimum value of field intensity. Something must
be known of the noise level and reception conditions in each 10-
cality and also of the competition from rival stations. The re-

quirements for primary coverage may vary by large percentages

-96-

in different localities. For commercial surveys, it is usually
convenient to show primary coverage for daytime and primary cover-
age for night separately.

The reason for this is that in the greater majority of cases
the night time primary coverage area is decreased because of in-
terference from other stations. This interference may be because
of heterodyning with stations on the same frequency in the case
of local or regional stations, or because of cross-talk from
stations on adjacent channels.

Primary and secondary coverage having been determined, the
statistical data should be determined for the areas defined. This
data includes among other things, the pOpulation of the area, the
:number of homes, and the number of radio sets. All this infor-
Ination is of general interest to any advertiser and is statisti-
csal data of primary importance.

Next in importance is an analysis of the economic life of
each area under study. The p0pulation should be divided into
ltrban and rural and the average number of potential listeners-in
ill each subdivision should be shown. Information as to the num-
‘bear and kinds of wholesale and retail concerns, total wholesale
a11d retail receipts for a year, number of employees and payrolls
153 of great importance in determining market conditions for a
c3ertain area. I

All of this statistical information is available from of-
IIilcial government sources such as Department of Commerce bulletins.

The third division of data, coming under the heading psycho-

l<Dgical, is much more difficult of analysis and is more Open to

 

 

IQ

-97..

argument and error. Under this heading might come the percentage
of buyers to the potential audience. This last percentage is

the one in which the station and the advertiser are most vitally

interested and the one which is the most difficult to determine.

However, from the law of averages it follows that the greater
the potential audience the greater the number of buyers. The
psychological part of the survey is tied in with the engineering
aspect in the following way. It is obvious that in a locality
where several stations may be tuned in with equal clarity of re-
ception the average listener will be influenced only by program
appeal. In areas where the reception of one station is better
than any other, that station will have the greater percentage of
listeners regardless of program, and in areas where service from
only one station is available, ype of program does not enter to
any great extent in an estimation of listening public.

In areas where program appeal influences the number of per-
sons listening, unsolicited program response by letter or tele-
phone, or regular listeners' surveys are about the only way of
estimating a listening public, and in most cases these methods are
very indefinite. They are not accepted by the Federal Radio Com-
mission at hearings and are not very conclusive evidence to pre-
sent to an advertiser. Hence, it may be stated that the thing of
greatest value in a commercial survey is the engineering data.
This is, of course, made more valuable by an analysis from the
statistical and psychological viewpoint.

An outline of a commercial survey should then incorporate

the following data:

I . ENGINEERING:

 

l.

2

3
4.

Determination
Determination
Determination

Determination

II. STATISTICAL:

 

of
of
of

of

primary daytime coverage.
primary night time coverage.
secondary daytime coverage.

secondary night time coverage.

(Average
(1. POpulation of each area (number of
(Urban (potential
(a) Potential-(2. Number of homes in each area -( -(listenerss
listeners ( (Rural (in each
(3. Number of radio sets (home.
(1. Wholesale outlets (Number of em-
( — (ployees and
(2. Retail outlets (total payroll
(3. Total wholesale receipts
(b) Market —(
information (4. Total retail receipts
£5. Manufactured products
I

O}
0

Agricultural products

The information coming under the head of psychological data

cafll best be determined by the station owner.

SPECIAL CASES OF FIELD INTENSITY SURVEYS:

 

A special instance intensifying the value of field intensity
measurements in presenting a case before the Federal Radio Commis-
sion is shown in the cases of KFPY vs. KSEI, FRC dockets 2008-9-10
and Federal Radio Commission vs. KCIR, FRC docket 2011.

The start of these cases dates back to 1932. At this time
KFPY at Spokane, Yashington, was operating on a frequency of 1340
kc., KSEI, at Pocatello, Idaho, was operating on 900 kc., and KGIR
at Butte, Hontana, was using 1360 kc. The frequency of 890 kc.
was at that time a Canadian shared frequency, and according to in-
ternational agreement was not available to stations within_2r0
miles of the border. In May, 1932, the frequency of 890 kc. was
released by the Canadian government, which action made this fre-
quency available to both KFPY and KSE . Both stations applied
for it at the same time and according to rules and regulations of
the Federal Radio Commission, a hearing of the applications should
have been held. For some reason the application of KSEI was
granted without a hearing. KFPY promptly appealed the case and
won the appeal, a hearing of the case being granted and set for
the seventh day of June, 1933.

KGIR now entered the case by applying for the frequency of
1340 kc. in case it was released by KFPY. The author was retained
by KFPY and KGIR to make field intensity surveys and to act as an
engineering witness at the hearing. A case of this kind naturally
involves depositions and proof of the relative value of programs

and general use of the station to the listening public, as well

-100—

818 engineering data. In the following symposium, the engineering
Elspects of the case alone will be considered.

KGIR is a low power regional station Operating with a day—
‘tzime power of one kilowatt and a night time power of 500 watts.
Ift is the only station in Butte, Montana, a city of approximately
‘$(),000 population. KFPY is a low power regional station operating
xmtith a full-time power of one kilowatt. It is one of four sta-
‘tiions in Spokane, Washington, a city of 115,000 population. The
crther stations are RJQ, 590 kc. low power regional station, 2000
VVElttS daytime and 1000 watts night time power; KGA, 1470 kc. high
IPCDwer regional, 5000 watts full time power; and KFIO, 1240 kc.
3Lc>ca1 100 watt daytime station.

KSEI is a low power regional station operating on a daytime
IDc>wer of 500 watts and a night time power of 250 watts. It is
13lie only station in Pocatello, Idaho, a town of 18,000 pOpulation.
3:T1 the original application KSEI based their claims to the 890 kc.
IFrequency on the basis that when Operating on 900 kc. they ex-
IDerrienced severe night time interference from KHJ at Los Angeles,
<3Derating on the same frequency, and that they were the only sta-
13i.on which served the area around Pocatello with a daytime signal.

In building up the case from an engineering standpoint, it
Was thought advisable to incorporate the cases of ICFPY and KGIR

iJJto one on the basis of better radio service to the Northwest,
El‘nd to make field intensity surveys on all stations involved. The
3First survey was made on KGIR. An RCA Field Intensity Meter Type
'TMV 21-A such as has been described in Chapter Three was used on

these surveys.

   
   
    

anyor near -ut e, i ntana.

line File

9 I‘ELW.

I
‘1.

Attenuation in t

~101-

KGIR SURVEY:

 

Butte is situated three miles west of the Continental Divide,
which twists and turns brokenly until it bounds the Butte terri-
tory on the north and south as well as the east. The terrain in
this section of the country is very mountainous and broken and the

roads are very winding

0’

as may be imagined. Butte itself is built
on a mountainside which has been termed the richest hill on earth,
containing as it does some of the deepest and most productive
COpper mines in the world. As the altitude of Butte is 5755 ft.,
it is advertised as the city a mile high and a mile deep. The
soil, where there is any, is of decomposed granite and is nearly
devoid of vegetation.

In laying out radials for a survey of this territory, it was
found to be near an impossibility to make measurements at points
falling very close together on any one radial. Especially was
this so at the time of year when the survey was taken because
many of the roads and passes were still snowbound. Some of the
pictures accompanying this article show the snow conditions in Kay.

TOpographical maps were secured from the Geological Survey,
Department of the Interior, for this territory as well as for Poca-
tello and Spokane territory. After consulting these maps and Hr.
E. B. Craney, owner and manager of KGIR, who knew the territory
thoroughly, it was decided that the only thing to do would be to
take measurements at the usual intervals on what roads could be
traversed and to draw radials through the thickest of them and
pull these measurements in to the nearest radial. The usual

method of making general contours could then be used.

-102—

 

 

 

 

 

May 10 1935 ho'”hea3t of Butte, Montana.

 

 

' woaomu MONTAM 3,: j ‘. o. + i. 1.
Continental Divido “2:5. , g #2,

 

 

 

 

L 4

Making Field Intensity Meas— Scene near Butte Montana
uremente on KGIR Butte,hontana

-lC$-

The car used was Hr. Craney's Buick sedan, which he drove
throughout the entire group of surveys, during which time a total
of over 5000 miles was traveled. The author and an assi tant,

Jr. R. P. Stewart, handled the test set which was set up outside
the car on the swivel tripod at each measurement. The time was
short and there was much work to be done_before the hearing. A
pepular account of the experiences encountered on this trip has

no place in this engineering thesis, but it might be stated in
passing that the thrill of traveling at high speed between measure-
ments on winding mountain roads will always linger in the author's
memory.

As there was no other station laying down a daytime signal
in the Butte territory, it was thought advisable to extend the
survey out to limits below 100 microvolts per meter, as this could
be considered a serviceable signal under these conditions. As
may be seen from the contour map, this extended the survey in some
cases 70 miles from Butte.

The reason for KGIR wanting to change from 1360 kc. to 1340
kc. was because of severe night time interference from station KGJR
at Long Beach, California, Operating on the same frequency. This
interference was observed many times by the author. It was noted
that in addition to cross-talk there was a modulation of the audio
components by the difference in carrier frequency, which in this
case ranged from about 2 to 10 cycles per sec. Experience at the
Frequency Monitoring Station at Grand Island, Nebraska, had taught
that for suCh phenomena to occur, the relative energy of the

carriers must be in the neighborhood of 3 or 4 to l. The Federal

.mzmucoa spasm has: uwop sampddos

 

 

 

-104-

Radio Commission has determined that in order to avoid cross-talk
on stations operating on the same frequency the ratio of energy
must not be less than 20 to l. It was very evident that the inter-
ference fell within this limit, but it would be necessary to prove
actual ratios of field intensity. To do this, it was necessary
to measure the night time field intensity of KGHR when KGIR was
off the air, and vice versa. Fortunately, due to difference in
time, KGEB was on the air two hours after KGIR had signed off, so
interference measurements could be made without upsetting the
usual station routine. '

In order to speed up the work, the usual procedure was to
finish up daytime measurements at the end of one of the radials
and then come back to a point within 33 miles of the station and
wait until KGIR had signed off. The reason for the 33-mile limit
was because the Federal Radio Commission had guaranteed protection
from interference within the one millivolt field, which they ‘
claimed should extend in the case of a 500 watt station to a 33-
mile radius.(l) huch to our chagrin, it was found during the hear-
ing that this limit had been decreased to 17% miles for a frequency
of 1360 kc. However, enough measurements were found within this
limit to prove the point. After KGIR had signed off, measurements
were made on KGB? to a distance of about 15 miles from KGIR and
then a 30-mile interval followed before measurements were resumed 13
miles the other side of the station. By making this skip, two radi-
als could be finished before K033 signed off. By prearranged sched-

ule, KGIR then went on the air again and the route was retraced making

(1) Ring - Empirical Standards for Broadcasting - I.R.E. Pro-
ceedings, April, 1932.

-lOS~

measurements on KCIR at the identical points where those of K053
had been made. This procedure was repeated for several nights
until the territory between 15 and 33 miles radius had been pretty
well covered.

It is very difficult to make night time measurements because
of fading. This was especially true of KGER, where rapid fading
we0 generally encountered. This was not noted particularly on
the car radio equipped with automatic volume control, but was very
evident on the field intensity set. The needle of the output
meter was swinging up and down continually and in order to obtain
a comparison value quasi peaks were taken. These are peaks which
do not exceed a certain value 90% of the time. It was necessary
to set the 100p attenuator so that the needle would swing to the
usual reference point of 150 microamperes approximately this much
of the time. Such procedure naturally makes night measurements
slow work. It was noticed that there were no null positions of
the loop when measuring the sky wave, which would indicate hori-
zontal polarization. At no time was it noticed that the position
of the loop had any effect on the signal. This would seemingly
indicate that the fading was from other causes than a shift in
polarization. Severe fading was noted on KGIR even at a distance
of 15 miles from the station. This was undoubtedly due to in and
out of phase conditions of sky and ground wave, although it is
very possible that in this broken country much fading is caused
by reflection from mountainsides. The 100p did show directional
effects on KGIR even at the 33-mile limit, indicating the presence

of some ground wave energy.

~106-

  
 

‘ 1?..3 7'".

‘ p‘f _
J? " '.

I ‘ 0; h Ei'l
.. M I i n 3&3

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‘.‘

 

 

Near Elliaton Montana May 10 1933

 

 

 

Clark's Fork River Northwest of Butte Montana

-107-

The daytime survey of KGIB and the interference tests between
K033 and KGIR having been finished, two days were taken to arrange
the data and make the usual contours. The result of the daytime
survey is shown in Figs. 28 to 31, inclusive, which include the
field intensity vs. distance curves and contour map. They will
be discussed later. The night time measurements were computed for
both stations and the field intensity ratios were spotted on a

:map at the point of measurement. The method of arranging this data

is shown in Fig. 32.

gpsni SURVEY?

 

The field intensity meter was again loaded in the sedan and
axlearly morning start was made south through Dillon, Montana,
51nd across the Monida Pass into Idaho. Starting at Spencer, Idaho,

Ineasurements were made on the following stations:

KID - Idaho Falls, Idaho - 500 watts — 1330 kc.
KSL - Salt Lake City, Utah - 50,000 watts - 1130 k .
KTFI - Twin Falls, Idaho - 500 watts - 1240 kc.

KSEI - Pocatello, Idaho - 500 watts - 890 kc.

measurements were continued on this radial to Pocatello and
‘then over a west radial as far as Rupert, Idaho, a distance of 60
Iniles from Pocatello. A return trip was made to Pocatello where
the night was spent in a tourist camp at the edge of the city. A
cabin was picked away from.any power line interference and the
equipment was set up in the cabin. Night time measurements were
made on the following stations: KSL, KSEI, KNX, KFI, KPO and KOA,
and an attempt was made to measure KHJ, but without success. Al-

though the set was tuned to KHJ for 15 minutes and the station

FIELD

Station KGIR - l kw.

May 9, 10, 1:5, 19:53

 

 

~108-

INT EI‘IS I TY LEA SUR EITETTT 8

Frequency 1360 kcs.

E — Millivolts/m

 

 

 

 

 

Ebp — C (City), 1 d - Miles
Radial a (NOrth) P - 22
MST :::~ 1" "" " ‘L
Time Location d E r T S S1 R
May 13 (map C) 100
10:20 am Mine dump on N. 0.55 239.0 6 10M .07 .05 15.0
Washington
1May9
11:00 am 5 , 0.73 149.0 15 1M .25 .14 19.1
benterville
Iflay 9
10:41 am 3 1.476 63.5 15 1M" .145 .07 14.0
May 9
10:50 am. 4 1.61 26.2 12 1M .07 .35 12.0
Hill "T" loca-
tion
be'l3 (map 1)
8:10 am 34 4.30 14.9 9 100 .36 .25 18.8
be 10
4:56 pm XII 38.000 .0382 9 l .11 .07 15.75

 

 

 

 

 

 

 

 

 

 

 

-109-

FIELD INTENSITY MEASURWHWNTS

 

Station KGIR - 1 kw. Frequency 1360 kcs.

May 9, 10, 1933
E - Millivolts/m

Map C (City), 1 d - Miles

 

 

 

 

Radial b - (N. E by N.) P - 22
£WWJ
Time Location d E r T S 81 R
may 9 (map 0)
11:28 am 1.38 11.2 9 l M .04 .02 9.0
Granite Ht. mine
May 9 .
11:36 am 10 1.61 17.4 12 1 M .035 .02 16.0
Near Clark mine
May 9
11:42 am 11 1.68 19.0 12 100 .33 .2 18.45
Blackrock mine
flay 10 (map 1)
1:41 pm XX 13.0 1.255 12 10 .29 .18 19.65
Elk Park
may 10
2:00 pm X 21.8 1.058 12 1 .240 .150 20.0
Basin
May 10
2:07 pm X 22.1 .805 12 1 .185 .115 19.75
Basin-end near
Helena
May 10 .
3:25 pm X6 46.0 .023 9 1 .05 .035 21.0

 

 

 

 

 

 

 

 

 

 

-llO-

FIELD INTENSITY MEASUREMENTS

Station KGIR - l kw.

May 9, 10, 1933

 

Frequency 1360 kc.

 

 

 

E - Millivolts/m
Map 0 (City), 1 d - Miles
Radial c (N. E.) P - 22
Time Location d E r T S 31 R
May 9 (map C)
11:14 am 7 0.691 327.0 18 1M .43 .245 23.85
Anaconda mine
May 10
12:45 pm 13 1.7 44.75 15 1M .125 .065 16.25
Meaderville
May 9 ‘
12:08 pm 14 2.5 24.0 9 1M .075 .04 10.3
Hospital
May 10
1:19 pm 16 4.1 4.29 12 100 .095 .06 20.55
Continental
Divide
May 10 (map 1)
1:30 pm. 17 6.5 2.301 9 100 .05 .035 20.98
may 10 ,
May 10
2:30 pm. X2 25.0 .0264 9 1 .08 .05 15.0
May 10
2:35 pm X3 26.0 .047 9 1 .145 .09 14.72
May 10
2:50 pm X4 32.0 .0396 9 1 .12 .075 15.0
May 10
3:05 pm X5 36.5 .0249 9 1 .07 .045 16.2

 

 

 

 

 

 

 

 

 

_

-lll-

FDILD INTENSITY MEASUREMENTS

Station KGIR - 1 kw.

May 9, 11, 17, 1933

Frequency 1360 kc.

 

 

 

E - Millivolts/m
Map 0 (City), 2, 6 d - Miles
Radial d (s. E. by E.) P - 22
MST
Time Location d E r T S 81 R
May 17 (map 0)
10:58 pm 22 0.5 263.0 12 1 M .455 .275 18.3
th 9
1:03 pm 19 1.55 29.6 9 1 M .095 .05 10.0
May 9 .
12:55 pm. 18 2.0 49.8 12 1 M .08 .05 20.0
may 11 (map 2)
2:55 pm. 22.0 .199 12 1 .42 .27 21.6
May 11 (map 6)
3:18 pm 4 28.0 .132 12 1 .28 .18 21.6
may 11
3:25 pm. 3 31.2 .096 9 1 .1 .07 21.0
bad fading
May 11
3:50 pm_ 2 34.5 .059 9 1 .15 .1 18.

 

 

 

 

 

 

 

 

 

 

 

 

-112-

FI TIILD INTI-13113 IT Y 12.43133 ITII‘IIII‘TT 3

Station KGIR - 1 kw. Frequency 1360 kcs.

May 9, 11, 1933
E — Millivolts/m

 

 

 

 

Map 0 (City), 2 . d— Miles
Radial - e (S. E.) P - 22
MST
Time Location. d E r T S 31 R
May 9 (map C)
1:20 pm 21 0.47 246.0 12 l M .365 .235 21.70
May 9
4:07 am 40 1.09 65.5 12 1 M .15 .08 13.7
I
May 11 (map 2)
1:50 pm 43 3.5 29.0 9 1 M .065 .045 20.2
1:58 pm 1 4.75 15.70 12 100 .32 .208 22.3 :
b
May 11
2:16 pm 2 13.8 2.21 9 100 .051 .035 19.6
Iaiay 11
5:27 pm 10 25.3 .192 12 1 .44 .275 20.0

 

 

 

 

 

 

 

 

 

 

~113-

FIELD INTENSITY MEASUREMENTS
Station KGIR - 1 kw. Frequency 1360 kc.

May 9, 11, 14., 24, 1933
E - Millivolts/m

 

 

Map 0 (City), 2 d - Miles

Radial - f (South) P - 22

MST

Time Location d E r T S 31 R

 

may 24 (map C)
1:20 pm 30 0.4 277.0 12 1M .591378 21.40
Mack's Joint

May 9
2:43 am 31 0.7 172.0 18 10M .24 5135 23.05
Travonia Mine

May 14 (map 2)

11:15 am 40 20.5 0.8175 9 10 .19 .13 19.5
- Divide
May 14
1:52 pm 43 27.0 .139 9 1 .33 .225 19.25
Melrose
may 11
7:23 pm 17 40.5 .103 15 1 .17 tll 27.5
May 11

 

 

 

 

 

 

 

 

 

 

(local sunset 7:30 pm)

 

FIELD

Station KGIR - l kw.

May 9, 13, 14, 1933

-ll4-

II ET 331? S

ITY KEASURHMUNTS

Frequency 1360 kcs.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

E — Millivolts/m
13p 0 (City), 2 d - Miles
Radial g (s. w.) P - 22
mm —-—
Time Location d E r T S S1 R
May 9 (map 0)
3:00 am 32 0.96 65.8 18 1 M .145 .065 14.6
W. Platinum
May 13
9:00 am 51 1.35 76.95 9 l M .235 .165 21.2
t
May 14 22 .
2:30 pm. (map 2) 11.4 2.975 9 100 .075 .05 18.
Feely Divide
May'l4
1:40 pm 41' 23.0 .130 12 l .26 .17 22.7
Dewey Flat
May 14 I
1:45 pm 42 24.25 .1525 9 1 .37 .25 18.75
Wise River

 

FIELD

~115-

II‘IT ENSI TY 1‘31] ASUR IIIENTS

 

Station KGIR - l kw.

May 9, 13, 14, 1933

 

 

 

 

Frequency 1360 kc.

 

E _ Millivolts/m

 

 

 

lap 0 (City), 1 d - Miles
Radial h (West) P — 22
ABA—rm arc—L --——-
Time Location d E r T S 51 R
May 17 (map 0)
10:38 pm 101 0.50 197.0 12 1 M .3 .19 20.71
(0.5 mile Pwr.)
May 9 -
3:05 am 33 1.0 107.0 18 l M .21 .1 16.36
School of Mines
May 14
6:05 pm . 37 3.35 19.6 12 100 .45 .28 19.8
Rocker
May 13 (map 1)
9:20 am 35 4.85 16.0 9 100 .33 .235 22.3
Mammy's Shack
May 9
3:50 am 62 5.95 11.0 12 100 .19 .115 18.4
Silver Bow
May 14
5:50 pm 27 9.0 1.91 9 100 .055 .035 15.75
near Cracker-
ville

 

 

 

 

 

 

 

 

 

~116-

FIELD INTHNSITY MEASUREMENTS

Station KGIR - 1 kW.

May 11, 14, 24, 1933

Frequency 1360 kc.

 

 

 

 

E - Millivolts/m
May C (City), 1, 3 d - Miles
Radial i (N. w.) P - 22
.1181?
Time Location d E r T S 81 R
May 11 (mp G)
1:20 pm 34 0.8 196.0 12 1 M .425 .27 20.4
May 24 (map 1)
10:04 am 26 12.0 3.220 9 10 .535 .365 19.3
May 14
5:45 pm 25 17.7 2.370 12 10 .535 .335 20.1
May 14 '
5:30 pm 24 21.0 0.616 9 10 .17 .11 16.5
May 14 (map 3)
5:20 pm 28 27.2 0.462 9 10 .l .07 21.0
May 14
5:15 pm 5 33.0 0.147 12 1 .3 .195 22.3
May 14
5:04 pm 26 35.6 0.248 12 l .545 .345 20.7
May 14
5:00 pm 25 36.8 0.141 9 1 .34 .23 18.83
May 14
4:50 pm 4 37.75 0.1672 9 1 .43 .285 17.70
May 14
4:40 pm 3 39.25 .0725 9 l .19 .125 17.32
May 14 '
4:25 pm 2 39.5 0.1055 9 1 .25 .17 19.15
may 14
4:14 pm 1 46.5 .0785 9 1 .205 .135 17.35
slight fading

 

 

 

 

 

 

 

 

 

 

-117-

FIELD INTENSITY MEASUREMENTS

Station KGIR - 1 kW.

may 9, 10, 24, 1933

Frequency 1360 kcs.

E — Millivolts/m

 

 

 

 

Map 0 (City), 1, 5 d - Miles
Radial J (N. w. by N.) P - 22
MST
==:— :—
Time Location d E ][r T S 81 R
May 9 (map C)
10:30 am 1 0.759 191.5 15 1 M .305 .175 20.2
Eoulten reservoir
May 24
10:35 am (map 1) 18.0 0.445 9 10 .075 .051 19.1
Galen
be 24
11:00 am 19 28.0 0.232 9 1 .4 .27 18.3
Deer Lodge
May 10
6:07 pm. 14 37.8 0.138 9 1 .39 .25 16.05
Garrison
May 1 0
6:32 pm 15 44.0 0.183 9 1 .525 .335 15.85
Gold Creek
May 10 (map 5)
6:56 pm 1 54.3 0.1388 9 1 .37 .24 13.6
Drummond

 

 

 

 

 

 

 

 

 

~118-

FIELD INTEIIS I'I‘Y FEASIBEEETNTS

 

 

 

Station KGIR - 1 kw. Frequency 1360 kc.
May 9, 10, 11, 1933 E — Millivolts/m
. d - Miles
Miscellaneous readings not on radials P - 22
km?
Time Location d E r T S 31 R

 

 

(readings between radials; N. - M.W. by N.)

May 10 (map 1)

4:43 pm 10 38.8 .0616 9 1 .17 .11 16.5
May 10

4:30 pm 9 40.0 .0467 9 1 .11 .075 19.3
May 10

4:25 pm 8 41.3 .01875 6 1 .09 .055 9.43

(readings between radials: N.E. by N. 4 N.M.)
May 9 (map 0)

11:21 am 8 1.05 41.3 15 1M .115 .05 11.58
Speculator Mine

(readings between radials; F.E. 4 S.E. by E.)
May 9 15

12:17 pm. (map C) 2.55 19.55 9 1M .07 .035 9.0
E. of Sinbad Mine

(readings between radials; 3.3. by E. - S.E. by s.)

. May 11 (map 2)
2:47 pm 4 18.0 .254 12 l .55 .55 21.

May 11
2:28 pm 3 18.0 .241 9 10 .085 .051 12.85I

May 11
4:55 pm 8 22.8 .132 9 10 .04 .025 15.0

May 11
5:12 pm 9 24.8 .101 9 1 .255 .17 18.0

 

 

 

 

 

 

 

 

 

 

 

~119-

FIELD INTLMSITY wrasuawntwrs

 

 

Station KGIR - l kw. Frequency 1360 kc.
May 9, 10, 11, 1933 E - Millivolts/m
d - Miles
Miscellaneous readings not on radials P - 22
_MST
Time Location d E r T S 81 R

 

(readings between radials* S.E. by S. a South)
May 11 (map 2

5:43 pm 11 32.0 .102 12 1 .245 .15 18.95
May 11

5:55 pm 12 36.0 .0908 9 1 .27 .17 15.3
May 11

6:10 pm 13 41.2 .0485 12 1 .275 .11 8.0
may 11 ‘

6:45 pm 15 51.0 .111 12 1 .21 .14 24.0

(readings between radials; N.W. by N.)

May 10 (map 5)
7:12 pm 2 52.0 .1188 9 1 .3 .2 18.0

(readings between radials; N.w. by N. 4 North)

may 9 (map 0) - -

11:05 am 6 .596 204.0 15 1M .57 .2 17.65
Centerville

May-9 - '

10:56 am 2 1.25 65.5 15 1M .16 .07 15.14
Moulten Mine

May 10 (map 1) -

5:54 pm 15 57.8 .1955 9 1 .57 .56 15.42

May 10

5:27 pm 12 41.0 .0855 9 l .21 .14 18.05

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ee.mH He. 89. m 68H. 0.0m 86 ooum mHe 80.8
HH 562
¢
m.mH mo. 8H. NH mmo. o.om an mmuHH mac H
0H 862
mn.mH me. am. a 5mm. m.mm .85 omuH mHomLmo.m
HH me:
n
4m.mH H. pH. 5 H840. m.mm 2 ooumH mack H
HH he:
Repose 6.4H mum. «e. m oewH. c.mm an mH.H mHoa mH.n
oaneon poem. HH 56:
Howooq Roomy m
o.Hm so. H. e neeo. c.mm an omHOH meow H
oH he:
me.mH men. an. m mnom. o.nn an wouH
HH has.mHoM ee.m
H
mm.¢H 9H. mmm. a mneo. o.nn an mauoH mama. H
oH he:
mxhwaon can m Hm m H m c nOHpmooq ofiHB capam
noHpeeHereeeH
emeoH amen .Mpwm me .nHmem . HaHeam
c.mm I m am an:
moHHs . e nmeH .mH .HH .OH 5&2

a\mpHesHHHHs : m

.moM coma honmzdoah

mazmsmmsmams_wewmzmazH onHm

 

 

mHGM

mmwM

 

enoHpepm

 

 

Mommo HvzmmmmmmBZH

 

-121-

 

 

 

_

Hzoqson< mHHom ¥ _ A
wanpoE map o.¢N H. mH. H NH #050. 0.00 3d NouH mHGM bN.H
nonazl.wa0m p

080:9 .86 ooqu b.mN mso. HH. H NH NNoo. o.on .ad oouH mmcm H

NH he:
AmHmmm
go muHmpsov 0.6N mH. 5N. H NH meH. m.HN aw onuH meM mo.n
“Soon NH hm:
Hme wHHmHodnHo m
OHmza monwmv o.¢N mo. who. H NH bmno. m.HN ‘85 NnuNH mmem .H
NH 56:
n.NN nH. N. 0H NH 0mm. c.mH aw mmuH mH¢M 55.0
Axnmm MHmV m
Anamoowv o.¢N ¢H. HN. H NH HHH. c.mH aw OHNNH mmwm H
NH an:
mxnwaom can m Hm m a H m o mcngoOJ oaHa 0H9
cchonmezoo

 

 

o.mm ! m

mmHHa . e
a\mpHo>HHHHs . m

.mox oomH hoacswmnm

 

 

 

 

 

 

 

 

 

omeoH neon .Mnem HHH .eHmwm : HeHe
H% mm:

.nweH .mH .HH .OH an:

chM
mane mnoHHepm

 

Mommu MozmmmhmHBZH

mezmfimmbm<m2 WBHWZHBZH QHHHm

 

 

 

 

 

 

 

 

 

 

 

 

 

o.NN NN. NN. NH eeH. m.mN 88 NNHH NHNM NN.¢
NH 888
AOHNSE HH
68HN eHoV o.ON N80. NH. NH NNNo. N.NN 88 NHNHH mama H
NH 885
e.NN NmN. N48. NH HNN. o.NN 88 NouN mH8M_ NN.N
0H NH 862
AeeHm
.0 8688681 N.NN NH. N. NH emmo. o.NN 88 oNNOH mmcm H
NH 8N8
NH 888
N.NN NN. NNN. NH omN. c.mH _86 NHHN mHoN N.¢
HeHHeep e
-868 68888881 m.HN 80. 4H. NH memo. c.mH 88 ONNOH mmom H
NH 888
N.NN N. NNN. NH NNHN. c.mH .88 eNuN mHoM m.m
NH 888
N
o.NN mo. NH. NH aNeo. c.mH 8N NHHOH mama H
NH N8:
mxnwsmh cum m Hm m H m c noproOH QaHE oHpom
eonmeHNHp8me
memeHnm 8Hsa .HHweepHee . HeHeem
NN - m

mHOM Sony mmHHE I U
E\mpH0>HHHHE I H

.moM ONNH honodvmhm

mBZHEHmDm¢mS NBHWZMBZH QAmHm

 

 

N» 882
NNNH .NH .NH 888

chN
mmom meoHpepm

 

 

mMoono mononmgnoan

‘

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

_
o.oN No. NH. oH NH NNo. N.oN 88 NeuH mHoN Ne.o
Hmpnwzm mH
-eHN NeHmV NN.oH NH. NN. H NH NNoo. N.oN 88 NNNNH mmom H
oH N88
AonoeN 8881
18668 N.NN NeN. NHN. H NH NNHN. N.HN .88 oHuH mHoM NN.N
-HHem oHHoN NH 882
noo8H0_aonm #H
6H888 668881 H.NN NNH. oH. H NH mooo. m.HN 88 NNNNH mmom H
NH 888
1N8Hooe own“ N.NN NNN. NNo. H NH HNN. N.NN .88 mNuH mHoN o.N
NH he:
NH
“NeHHNNo 88v o.oN NH. NoH. H NH HNoH. N.NN :.oo"NH mmom H
NH 888
_
% 1N8Hoeu
Ni eon 88681 o.oN NH. 8N. H NH NNoH. N.¢N .88 oouH mHoM NN.H
. NH 88:
Amhonsoo Hm NH
-86H88886p8HV o.NN HH. NH. H NH NNmo. N.NN _88 NNMHH_mNoM H
NH
338889 28 m Hm m .H. .H m o :oprooH 083‘ 0.38
ooHpeeHNHpoeo , .au:uu-lulsgatnyunnuy:--11:11:11: ---sg::1i ,-:l::-
NN : m meNoHem 8H88 .HHeeepHee . HwHoem
Nfi 85:
mHoN 868N meHHH - o NNoH .NH .NH 888
8 mpHoeHHHHs . N
\ . mHoM
.mox ONNH honmsvonh mmwm mnoHpNPm

 

 

mMommo HoZfimflhmmBZH
mBZmEmmDmdME NBHmZmBZHlmquh

 

-124-

 

 

 

c.mm I m

NNHHE I o
8\NpHo>HHHH2 I a

.mo& ONNH hoaoswohm

 

mezmfimmbm¢ME_NBHmZMBZH QAHHh

 

 

 

 

 

 

 

 

 

 

 

31f... I. 11).).."1‘1 III!) )1! )IIIIII in!!! :1) III... gll‘l'lil’ )9

NMNH ghoumwhooo I HNHowm

 

o.NH No. No. oH N NNN. o.eN .88 NonN mHoM
NH 8N:
NH
neHeHmmof NnHoeen 6N1 I o.eN .88 NouHH mama
HH 8N:
NN.NH 8N. NNN. H N NNNH. o.oN 8N oNuN mHoM Ho.e
NH Nms
8H
o.oN H. NH. H NH oNeo. o.oN .89 oNuoH NNNN H
HH Nam
NN.NH NH. NN. H o NNNo. e.oN .8N NNNN NHNM NN.H
NH 8N2
NH
1HNNHONNNNNNOV o.NN No. NH. H NH NNoo. N.NN 88 oNuoH mmom H
HH 8N8
mmaqamn cam m Hm m a H m c noHpNooq NEHP oprm
:oHpNonchowm

NN Nu:
NNNH .NH .HH Nan.

mHoN
anon meoHprN

 

 

Mommo EDZfiMMhmHB%W

 

~125-

 

 

NNHHE I o
8\mpHo>HHHH2 I m

 

.Nox ONNH hoqmsvonh

 

 

 

 

 

 

 

mBZMQHmHmDmgH EHmZHpm/HH Bah

 

 

 

 

 

.9862 .mppom No
NpHo map N0 8m»
Inoo Nap .HNNPHB
IN8N8N m.mHoN No
space .H8 NN.
8\>8 NNH No NNN
Inohpm Hwanm w
888 mmom INNPoz N.NH NN. NN. H NH NNH. NN.o oN .8N NouHH
NH.NN8 mmom
H.NH NNo. No. oH N NNN. o.NN .88 oHuN mHoN NN.N
NH Na:
NH
No.NN NNo. NH. H NH NNNo. o.NN 8N NHuHH mmom H
HH 888
Nahuamn onw m Hm m a H m w noHpNooH QEHB oHme
%

oMNH :Bopownooo I HwHowm

Nw mus

NNNH .NH .HH Na:

mHoN
N888 NaoHprN

 

Mommo mozmmmhmHEZH

 

KFPY IN BUTTE TERRITORY
FIELD INTENSITY MEASUREMENTS

Station KFPY Frequency 1340 kc.
May 11, 12, 13, 1933 E - Millivolts/m
d - Miles

Map #1, 2, 3.

Radial - Boulder, 18 - mile hill, P - 22.5
Georgetown Lake

Time Location d E H r T S 81 R

 

May 15 (map 1)
12:52 am. 0 20.0 .107 12 1 .24 .15 19.8

May 12 (map 2)
10:21 pm 3 18.0 .160 12 1 .28 .19 24.3

May 11 (map 3
10:38 pm 25 36.7 .132 r 12 1 .26 .17 22.6

may 11 (map 2) 16.75 .090 9 1 .25 .16 16.0
12:10 am (Warm

Springs

Road)

 

 

 

 

 

 

 

 

 

 

No other stations on 1340 were heard, nor was any interference

eXperienced on this frequency.

 

.— ‘————

-I-n

FIELD INTENSITY SURVEY
KGI R. BUTTEJ'IOHTANA. 1.000 WATT-S '360

0,, II

        

   
  
 
 
 
  

. 9 l

    

 
 
 

O a -

"It“ VOLT'S

FIELD curen SITy
MllllVOLTS

"1630 VOLTS

HICRO VOL TS

Menu. 00.. I. 1...:
' “0!.“

F I G. 28. oasmuca m mus

INTENSITY SURVEV

FIELD
KG I R. BU‘I’TE.MONTANA

IafiOKC.

IOOO WATTS

 

dOSNstt

  

>LLN tubt.

T1

IF...) ~dd~t

DJfl~h

up v... 0.2!

 

 

 
 

”5.0., ‘0‘:

f

DISTANCE m MILE-3..

FIG 29.

FIELD INTENSITY suavev
KGIR BUTT: MONTANA Iaoo WATTS I‘seoxc.

  
 

O

 

 

.91. ~

 
   

MILL! VOLT‘

 
 
 

1"

"I‘ll

   
   

new m rcnsn y

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HIMOWlTS

 

HA... “4.

 

  

 

 

 

_ 'I UQHULLHEWJHJ—AysuL—H.'4+ILA,!§.—__fi1|_!%

 

_=__=.WW

 

CG

5‘
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Half}: Lumnq ' _ - 1 I " " ,‘ , I _-_ M I . - _ '
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-137-

could be faintly identified, the signal was too weak to measure.
The results of these measurements accompany this article.

The next day, measurements were resumed on the same stations
on which measurements had been made the previous day. A south
radial was taken this time and measurements were carried out to
a point where the signal of KSL predominated that of '°E . Al-
though this was only a sketchy survey, the extent of the distance
to which the signal of KSEI predominated could be determined on
three radials and also what other service was available within
the Pocatello territory both day and night. It also proved that
the signal of KHJ did not cause interference with KSEI within the
one millivolt field. A map showing the area in which the signal
of KSE predominated is shown in Fig. 33. Field intensity curves
for KSEI and KID appear in Figs. 54 to 57, inclusive. The only
excuse for making such a sketchy survey was lack of time. To ac-
complish what was done in two days meant traveling at high speed
between measurements with little time out for meals and sleep.

The return to Butte was accomplished that night and after a
day Spent in arranging the data of this survey, the meter was
again put aboard and a trip made to Spokane where the last survey
was made.

KFPY’SURVEY:

This survey was somewhat different than the rest in that it
was desired to prove that the attenuation of KFPY on 1340 kc. was
much greater than it would be on 890, and that the change in fre-
quency would benefit more peOple in Spokane territory than it
would in Pocatello. It was also desired to show the shape and ex-

tent of the field pattern of KFPY.

-128-

DAYTIME FIELD INTENSITY MEASUREMENTS

POCATELLO IDAHO Ant .

§TATIONS AND FIELD INIENSITY I5 MICROVC

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

canon t LTS PER METER
B d . 1 . T KT K
_ KS I in mi KID d film; KSL FI DY;
Spencer 34 53 52
bubois 52 97 58
Hamer 155 70 440 50 124 27
Roberts 192 2' 1500 15.5 155 .58
Idaho Falls 250 45 150000 .55 75
50500 1:13 _
Firth 500 55 1050 14.5 155
Blackfoot 900 25 590 86.5 197 ___
American '-
Falls 1840 22.5 108 00 550 140
Rupert 144 55 155 780
Pocatello 51000 w 1. I‘—
* 40100 N 1. 158 48 275 7c
' 25200 n 2. 102 4' 555 75
a 55500 s 1.
Inkom 1250 11 I 45 50 555 ';—-
McCammen 551 19.5 500
Downey 220 54 570
Oxford 92 45 1450 50

 

 

—129—

uIesr TIHL FIELD INTENSITY hEASUREMBsTS

LOCATION: Tourist camp in Pocatello,1daho.

 

DATE: May 16 and 17, 1935

§TATION TIME E Microvo1t§2per meter
KTFI Twin Falls Idaho 10:00p 222

KSL Salt Lake City 10:10 5100

KNX Hollywood 1C:32 910

KOA Denver 11:00 385

K00 Oakland 11:18 750

KPO San Francisco 11:43 2700

KFI Los Angoles 12:28a I720

KHJ Los Angeles Could not measure. Below sensitivity of

set. Was tuned to station for 15 minutes.
Heard station identification.

KPO San Francisco 12:57a 1100

Measured KSBI at 10:033as 26500 microvolts. Station at this
time was supposedly on 250 watts power.

Many other stations were heard but not identified.

 

      
 
    
     
 

  
  

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I

 

mIQrJoZJJ... t. 3233...: 015:1... .

MILES FROM STATION
WEST RADIAL

—1ao-'

To prove the difference of attenuation on different frequen-
cies, measurements were made on three stations at each point where
the test equipment was set up. Frequency allocations in Spokane
were excellent for attenuation data. KHQ on 590, KFPY on 1340
and KGA on 1470 kc. gave three Wide—spread points within the broad-
cast band. The time available did not permit an extensive survey
to be made, so measurements were made on y on four radials: north,
east, south and west of Spokane. As may be seen from Fig. 53,
there are roads running radially in these directions from the sta-
tions. This greatly speeded up the survey. Although the stations
measured are all Operated on different daytime power, this makes
no difference in data taken for the purpose of determining attenu-
ation because attenuation factor is computed as the ratio of field
intensity vs. distance at a point Where attenuation has set in to
the field intensity vs. distance at a close-in point where no
attenuation is expected. If comparisons of the efficiency of the
different stations are desired, it is easy to reduce each station
to a one—kilowatt basis by dividing the field intensity by the
square root of the ratio of the power to one kilowatt. It nay be
proven mathematically that the field intensity varies as the square
root of the power ratio, and the author, for his own satisfaction,
has experimentally proved this to be so a great many times.

Curves of field intensity against distance were plotted f(r
each station on each radial. These are shown in Figs. 38 to 45,
inclusive, both on ordinary cross section paper and on logarithmic
paper. For convenience each station was reduced to a one—kilowatt

basis.

 

 

. . - -345-

-. .‘_.J [fl-J 13,/11,111
- k

'- ' """L'x

 

- -‘ u” . ..nu-M‘

- At4--vo fi‘

‘
4
,4
D >-
F— {Ff 7 ,1
/' <

 

 

 

Antenna and towers. KFPY Spokane Washington.

-131-

Local shadowing effects should not appear in curves showing
general attenuation. As local shadows show up better on cross sec-
tion paper where the inverse distance curves appear as a hyperbolic
function, the data was first plotted on it. Then as exnlained in
Chapter Four, a dotted line connecting the peaks was drawn. Points
were transferred from this line to logarithmic paper. Attenua-
tion factors for each frequency were computed for distances of ten,

twenty and thirty miles from the equation

3 F. a.
A F0 do

where Fo _ field intensity at distance dO where no attenuation exists

F.

field intensity at distance d1

d1 any distance where attenuation factor is desired.

Curves were then plotted showing attenuation factor vs. fre—
quency for each of these distances. These are shown in Figs. 46
to 49, inclusive. From these curves the attenuation factors for
890 kc. were obtained.

It was now possible to compute theoretical field intensity vs.
distance curves for a one-kilowatt station on 890 kc. of the same
antenna and radiation efficiency as KFPY on 1340 he. In other
words, it could be shown graphically what increase in field inten-
sity would be obtained by making no other changes in KFPY other
than changing the frequency from 1340 he. to 890 he. These theo-

retical curves are shown in Figs. 50 and 5|. They were obtained

for each radial from the formula

2 F”. a. A
F. a.

where F1 . field intensity at distance d1

 

 

Fl is computed for distance d1 - 10, 20, 30 miles

—132_

F0 - measured field close to station
dO - distance in miles at which F0 is measured
A : attenuation factor for frequency 890 he. taken from

attenuation factor curves for each radial.

Four definite points were therefore available for each radial,
as one close-in point on each radial was common to both 890 and
1340 frequencies.

On the pepulation map shown in Fig. 52, the 500 EX contour

m
for KFPY from actual measurements on 1340 he. was compared with
the theoretical contour shown for KFPY on 890 kc. By counting the
dots between the two contours it was possible to show the increased
number of peOple who would reside within YFPY'S 500 Ez_fie1d.

0n the same map the 100 33 contour for KGIR andlihe 500 EX

m m
contour for KSEI were shown for each frequency involved. As the
frequencies 1360 and 1340 were so close together, no great differ-
ence in field intensity due to change in attenuation factor would
be expected. The greatest advantage expected in the case of KGIR
would be the elixination of the night time interference from K033.

In the case of ISEI, no appreciable difference in field in-
tensity would be expected from a change in frequency of ten kilo-
cycles due to change in attenuation. As no measureable signal could
be obtained from station KHJ on 900 kc., it was assumed that this
signal was below 20 21, which would not cause interference within

m
the one millivolt field of KSJI, based on the Commission figures
of a necessary 20—1 ratio between signals on the same frequency.

To recapitulate, the facts brought out by these various sur—

veys from an engineering standpoint are as follows:

—133-

1. Under the present conditions, with KGIR on 1360 kc., KSEI on

890 kc.
(a)

(b)

(c)

(d)

(e)

(f)

(a)

(h)
(i)

and KFPY on 1340 kc.,

KGIR suffers severe night time interference from

KGER operating on the same frequency of 1360 kilo-

cycles.

KGIR night time signal free from interference is

limited to a maximum of 15 miles radius.

The daytime signal for KGIR is shown to the 100 22

level. ' m

{FPY could be heard consistently at night in KGIR

territory without interference from other stations

on the same frequency.

The territory dominated by the daytime signal of KSHI

is outlined and the daytime service in this territory

by other stations is shown. The 500 EX contour for

KSEI is shown. In

The night time field intensity of some of the stations

whose signal is available in KSEI territory is shown.

It is proved that if KSEI was put back on the previous

frequency of 900 kc., no interference would be exper-

ienced from KHJ, Los Angeles, operating on the same

frequency.

Attenuation is much greater on 1340 kc. than on 890 kc.

The 500 uz_contour of KFPY is shown for both 1340 kc.
m

and 890 kc. under the same conditions of power input,

antenna and radiation efficiency.

-134-

2. Under conditions incorporating the desired changes, with KCIR
on 1340 kc., KSEI on 900 kc. and KFPY on 890 kc.,

(a) The night time field of KGIR would be at least as
great as the daytime field.

(b) The field of KSEI would remain unchanged.

(0) The area of the field of KFPY would be increased ap-
proximately 2% times.

(d) The number of people to whom.a 500 21 field from
KFPY is available would be increasednby approximately
40,000.

(e) In view of the above facts, better radio service to
the Northwest would be obtained without inflicting
hardships on any of the stations involved if the above
changes were made.

All of the above data, together with the necessary maps and
characteristic curves was submitted to the Federal Radio Commission
by the author while on the stand as an engineering witness in the
case. The other evidence relative to programs and use of the sta-
tion for the public good was given by Mr. E. B. Craney and Mr. T.
W. Symons, Jr., owners of stations KGIR and KFPY, respectively.
Although the case was weakened from their standpoint by the refusal
of the Commission to allow KGIR and KFPY to combine their cases,
the value of the testimony submitted is Shown by the following
reports of the examiner. Only excerpts pertaining to the engineer-
ing testimony are given.

ECERPTS FROM wmuxarma's REPORT jsov:_
"On May 16 and 17, 1934, a radio engineer made field intensity

measurements of the signal of KSEI Operating on 890 kc. during

-135-

daylight hours, a total of 17 such measurements being made: 7 to
the north of Pocatello, 2 to the west, 5 to the south and southeast
and 3 in the city. Based upon these measurements the 500 micro-
volt contour of KSEI was plotted as extending about 32 miles north
of the station, 21 miles to the south, and 45 miles to-the west.

No measurements were taken in an easterly direction because of the
absence of suitable roads. Within this estimated 500 microvolt
contour, the pepulation is approximately 38,000. In a rural area
where the noise level is low, a 100 microvolt signal provides

under average conditions a fair service. While no contour for

the 100 microvolt signal of KSEI is plotted, it undoubtedly extends
a considerable distance beyond the 500 microvolt contour.

"During the same period measurements were made of the signal
strength of Station KID at Idaho Falls, and Station KTFI at Twin
Falls, Idaho, from which it appears that each of these stations
lays down a signal of 100 microvolts or better in portions ofothe
service area of KSEI. Similar measurements of Station KSL at Salt
Lake City, tah, indicate that that station has a signal intensity
of at least 100 microvolts per meter throughout the KSEI territory,
but is subject to some fading. Additional service is received
during night time hours from distant stations.

"Due to the fact that KSEI is Operating on 890 kc. pending
decision on these applications, it was of course impossible to ob-
tain measurements with reference to its Operation on 900 kc. It
is the contention of KSEI that its service area was seriously cur-
tailed when operating on 900 kc. by heterodyne interference from

KHJ, a one kilowatt station at Los Angeles, California, approxi-

—136-

mately 720 miles from Pocatello. Under average conditions K831

and KHJ should have a geographical separation of 1000 miles to
avoid objectionable interference, and while there are no measure-
ments upon which the actual limitation upon KSEI's service area

can be determined it is probably a fact that a greater coverage

is Obtained by KSEI on 890 kc. han on 900 kc. Attempts to measure
the signal strength of KHJ in the city of Pocatello were unsuccess-
ful due to the fact that the signal was not of sufficient strength
to be measured, although the modulated signal was received and

the call letters and some announcements were heard. Assuming the
equipment capable of measuring a 20 microvolt signal, this would
indicate that KHJ would restrict the service area of KSEI Operat-
ing on 900 kc. to about its 400 microvolt line. Under average con-
ditions it would be expected that KHJ would limit the service of
KSEI to somewhat within its 1 millivolt contour.

"On May 19, 20 and 21, 1933, a radio engineer made field in-
tensity measurements of the signal of Station KFPY, operating with
power of one kilowatt on 1340 kc. These measurements were taken
on radials extending in the four cardinal directions; 14 being aken
to the east, 15 to the north, 13 to the south and 16 to the west.
During the same period similar measurements were made of the signal
of KHQ operating with two kilowatts power, and of the signal of
KCA Operating with five kilowatts power. Computations made from
these measurements indicate that the attenuation factor is less
on the frequency 890 kc. than upon the present frequency of KFPY,
namely 1340 kc. It appears that the Operation of KFPY on 890 kc.

would more than double its present service area.

-157-

"Various contours of the signal strength of KFPY were plotted
from the field measurements of that station. Its 500 microvolt
line extends about 13 miles to the north of the transmitter, about
14 miles to the east and west, and about 30 miles to the south.
Within this area there is an estimated pepulation of 135,000. In
the event the station is operated on 890 kc., the estimated popu-
lation within the same contour is 175,000, of which number 2,000
are in the state of Idaho. ;

"CONCLUSIONS: Objectionable interference will not result

from the Operation of either KSEI or KFPY on 890 kilocycles. Upon

-_ .A._

consideration of the facts shown, including a comparison of the

public service records of the two stations, and the areas and pep-

ulation served and preposed to be served by each, it appears that

as between K831 and KFPY, public interest will be better served

by the operation of the latter station on 890 kilocycles. 1
"It is accordingly recommended:

1. That the applications of Radio Service Corporation
(Station KSEI) for medification of license and modification of
construction permit, be denied.

2. That the application of Symons Broadcasting Company
(Station KFPY) for modification of license,_be granted.

Ralph L. Walker,
Submitted September 21, 1933. Examiner. "

EXCERPTS FROM EE‘EIN’ER'S REPORT #509:

"KGIR, Incorporated, seeks a change in_frequency from 1360
kilocycles to 1340 kilocycles, if and when Station KFPY, Spokane,
Washington, vacates the latter assignment. On September 21, 1933,

it was recommended (Examiner's Report No. 507) that the applica—

-138-

tion of KFPY to change frequency from 1340 kilocycles to 890
kilocycles be granted.

"On the basis of field intensity measurements of KGIR made
during the day when the station was Operating with 1 KW power,
contours of KGIR to and including the 100 microvolt line were
plotted. The contour map discloses a very irregular service pat-
tern, the 500 microvolt contour extending approximately 24 miles
to the north and to the south, 13 miles to the east and 19 miles
to the west. The lack of uniformity in the pattern is probably
due to the fact that the country is mountainous and the soil
mostly composite granite.

"Station KGER, located at Long Beach, California, operates on
the frequency used by the applicant station. The geographical
separation between the two is 925 miles, whereas the separation
recommended for the purpose of avoiding objectionable interference
within the one millivolt area is 1000 miles. 0n Kay 10, ll, 12
and 13, 1933, field intensity measurements of the signals of K013
and K ER were made at night at a total of eighteen points within
a radius of 33 miles of the applicant station. The two stations
were not measured at the same time for the reason that neither
could be measured when the other was Operating. At a point 13
miles northeast of KGIR the signal strength of that station was 986
microvolts, as compared vith a KGBR signal of 111 microvolts, the
ratio of the KGIR to the KGER signal being 9.77 to l. A measurenent
made 20% miles west of KGIR disclosed the signal strength of that
station to be 635 microvolts as compared with KGJR'S signal of 93

microvolts, a ratio of 6.78 to 1. A measurement made at a point

-l$9-

33 miles west of north of the KGIR transmitter disclosed the KCIR
signal to be 203.5 microvolts and the signal of KGER to be 73.5
microvolts, a ratio of 2.77 to l. A single measurement of KGBR
made at a point fifty-five hundredths of a mile north of HG R's
transmitter disclosed a signal strength of 105 microvolts.

"It is generally recognized that a ratio of 20 to l of the
desired to the undesired signal is necessary to provide satisfac—
tory reception. While a majority of the field intensity measure-
ments were made beyond the 500 microvolt contour of KGIR the
ratios shown would indicate that there is probahly some objection—
able interference within the one millivolt contour of KGIR.

"The stations now assigned to operate on 1340 kilocycles
(assuming that KFPY will be transferred to 890 kilocycles) are a
sufficient distance from Butte, Montana, that objectionable in-
terference would not be expected from the Operation of KGIR on
that frequency, nor would the quota situation be in any wise
changed by the assignment of KGIR thereto.

"CONCLUSIONS: Interference now exists within the one milli-
volt contour of Station KGIR. In the event KFPY vacates the 1340
kilocycles assignment, this interference can be eliminated by the
assignment of KGIR to that frequency, to the benefit of the pub-
lic and without detriment to any other station.

"It is accordingly recommended that the application Of KGIR,
Incorporated, for modification of license, be granted.

Ralph L. Walker
Submitted September 26, 1933. Examiner.

H

Note: March 23, 1934, the Federal Radio Commission granted the
application of KFPY and KGIR and denied that of KSE

-l4:0-

FIELD INTENSITY MEASUREMENTS

Station: K F P Y FREQUENCY: 1340 Kc.
Date: May 19 8c 20, 1933 P-_-_ 22.5
Map: Spokane County Radial: North

me Loca ion '1:
y 19

O

ay
0‘50A

 

~141-

FIELD INTENSITY MEASUREMENTS

Station: K G A FREQUENCY: 1470 Kc.
Date: May 20, 1933 P: 18.7
Map: Spokane County ’ Radial: North

me cha on

 

Station: K H Q P;115 FREQUENCY: 590 Kc.
Time Location S 31 R

05

* O

 

-142-

FIELD INTENSITY MEASUREMNTS _
Station: K F P Y FREQUENCY: 1340 Kc.

Date: May 19, 1933 P: 22.5
Hap: Spokane County ' Radial: East

me ca ion 1
2 7

 

-l43-

FIELD INTENSITY MEAsunmmngs

 

 

Station: K G A FREQUENCY: 1470 Kc.
Date: May 19 8c 20, 1933 P: 18.?
Map: Spokane County Radial: East

no noca on S 81 R
Y

2 O 000.

5 O 8500 2

 

sinion: K H q P- 115 FREQUENCY: 590 Ko.

inc Location d S S]. B
y 19

 

 

 

 

—l44-

FIELD men; mmmmmrs

Station: K F P Y FREQUENCY: 1340 K0.
Date: May 21, 19:53 P: 22.5
Map: Spokane County #1 & Map 2 . . Radial: South ;

Time Location d E S 51 R
3 na A-36 49 6

*

 

 

 

 

-l45-

FIELD INTENSITY MEASUREMENTé
Station: K G A FREQUENCY: 1470 Kc.

Date: May 21, 1933 P=18.7
lap: Spokane County #A & lap 2 Radial: South

no Location d E S

5

O

ation: K B Q

no Loca ion

 

 

 

 

-l46-

FIELD INTENSITY MEASUREMENTS,

Station: K F P Y FREQUENCY: 1340 Kc.
Date: May 21, 1934 P: 22.5
nap: Spokane County #1: a. map #1 Radial: want

me Loca ion (1 E 1

0 Ma A~22

 

-l4:'7-

FIELD INTENSITY MEASUREMENTS
Station: K c A ' ' ’ FREQUENCY: 1470 Kc.

Date: Ray 21, 1933 P: 18.?

Map: Spokane County #A 8: Rap #1 Radial: West

Time Location (1 BER S 31 R

10:07A he Ap22 5 25 9800 227 2

0' Ar 6
2

a

Mo

 

Station: K H Q P: 115 FREQUENCY: 590 EC.

Time Location :1 S 1 R

 

:4

SPOKANE TERRI‘I‘ORY

ATTEHUATIO H Conves ~

+
.
h
.4
.
o

 

H|LE$ FRO" STATUOH

.3

 

H

ATTENUATIO" Canvas — SPOKANE. reaanony

FIG.4O

.—
m
o
A
R

WEST

KHG- ssoxc; KGA - I470 Kc.

‘ 'quKCO

(who! «at 93023.! c. {.3535 043....

 

DISTANCE. FROM STATION m HOLES

SPOKANE. Team'roay

ATTEHUATIOH CUR vgs

So

(-.-I 0

(“It

7 6
n~40>132l r: > :0tlbl.

nan-I.1

 

HILES Fnon STATION

 

flFJO)..—it

>~dJ~t

«o
006

,1.

40)....d.‘

>5..." :95: can»...

“Fl-0) 0K0.t

 

70,10

  

 

WIIICyh

KIWIL O a“. CO.. I. V.

MILES FROM STATION

 

FIGAS

3

 

 

  

7 6
thozaflt

   

  

1
n ...-0)....1-5

  

“PJO>.JJ=L

erOMOIQ...‘

     

nPdOsa 010.:

I V.. I0. “I”

ICWOMIOO.
W'IIC,“

 

['1 MILES

DISTANCE.

FIGA‘!

 

 

KIWI. A ”It. eo.. I. v.. NC. ‘10.
W I I I C".

STATION

MIIF‘ BOOM

“5.40)....2: mPJODOCU.‘ WPJO>OCO-z

>h.wzw._...: 9.3:“.

Fl6.45

 

97.0) ..1..!

‘4‘1‘ 1

 

nuns O “OI- OO.. I. I. no. ‘1'
“It.“

DISTANCE I" MILES

ar40>13=L PrJo>os.! hPJO>O¢9t
>twrmkz. 042.". .

FIG.46

     

IIOIIOIIDO.|.‘I

oo‘o‘ kl

.II>1|‘ Ilol

2 J”

  

... J 7. . .
1..... .. (n «champs turrdazuhbn‘

’ :2: 2: 3 2 x {.93 n 6.3251343.»

 

Fflequtucy n4 Kl LO‘VGLGS

a

u < u Kabul?-

torn:

  

3 2

(DIULIFI‘

 

l
I

5

M
n
U

E75, ow 'on'.

.

Mn

0

IQ’O

 

 

m KILOCVCLES

FREQUENCY

8 7
C O

chum u < .... (05.05. .Ito....<

:ruhh(

do... 05 3 a. x 08050 a 6.5.5.:

 

Fneauency IN KILocyoLes

FHL49

. ' o u n < u moru<nth 0. hit 3:” wuwufl—I.A_LAQ n .9.E.:...I§._EU

I III 'u- n. a: .1), Old... ‘ J‘LI,“

 

0
o

:3

¢

0

$fl6 é

o

v

.
A .
o .

R15

 

 

 

IriKILocycLes

FREQUENCY

F!6.50

 

   

P40).dd_!

098

\t» tut...

 

«5024...!
O 4.2»:

 

WFJ°)8O .t

m
«a
M.
f
f

    

wmutzlcm

IIU'I’IL O 3.... 60.. I. '.. NO. ”I”

|N McLes

D'$TANCI

 

 

  
 

W?JO>.JJ.—l

In ‘

.WFJ°>-dd.z
xtwtwrt. onE .

 

nPJ°>OIU=L

[CWOMI 60. 0.... ”..AD
WIIICV“

m HILtS

DISTANQE

 

 

 

 

 

 

 

 

 

 

L E G E N D

Inner contour around Sponane snows KFPY
present 500 micro-volt per meter field
with 1340 KC daytime measurements. Outer
contour shows predicted 500 micro-volt
per meter field of KFPY on 890 KB.

 

Small circle around Butte shows approx—
imate present coverage (night time) of
.KGIR on 1360 KC without interference
from KGER. Outer contour shows present
100 micro-volt per meter field of KGIR
with 1360 KC 1000 Watts daytime measure-
ments. With KGIR on 1340 KC it is pred—
icted that the night-time coverage with
500 Watts will be at least equal to the
daytime contour as shown.

 

 

Contour around Pocatello shows 500 micro-
volt per meter field of KSEI daytime mea—
surements. It is predicted that the field
of KSEI on 890 KC will not change mater—

ially on 900 KC. ‘

 

Each small circle represents 1000 people.

SCALE OF MILES ~ 1 inch = 53 Miles

 

 

~148-

KGIR ccwrppa 2:113:

 

Referring to Fig. 31 showing the field intensity contours
of KuIR, it will be noticed that the pattern of this field is very
much distorted. The 100 E1 contour to the east flattens out as
soon as it reaches the Conginental Divide, while to the south
and northwest the 100 31 contour extends out to a point. It will
be noticed that the swe?ling out of the contour to the southwest
is directly in line With the Pipestone Pass, while the shadow
just to the left of this protuberance is undoubtedly caused by
the Highland Mountains. The point to the south which includes
Dillon is probably caused by energy flowing up through the Deer
Lodge Pass and down through the Big Hole and Beaverhead Valleys.
The sladOW'to the southwest is caused by Kt. Fleecer, and the
extremely broken country characterizing the Wise River country.
There is another swelling out of the contour which includes Ana-
conda and extends nearly to Georgetown Lake. To the northwest
there is a shadow in the 500 21 contour in the direction of Deer
Lodge which can be explained 3: no other basis than that of great
attenuation due to the nature of the soil. In the 100 B! field
this is healed by energy feeding in from the sides and gfien the
contour swells out up the Clark Fork valley where much less atten-
uation might be expected. To the north there is a slight flatten-
ing out again which is probably due to the Continental Divide
swinging brokenly in this direction.

A study of the terrain and the radio field contour map seems

to indicate that the distorted pattern is caused by the alternate

shadowing effect of mountain peaks and concentration of wave front

 

 

J(£/V£ flfflf gyrfgrfipp/yf

 

 

.4 [M547 ”7in
- 8a rift/’69"

s‘ -

' 5

have. ~"*‘»-1"-‘ - ‘.
‘ ‘ ~ ‘ . _

 

 

 

-149-

energy through the various passes between peaks. The general
attenuation is high as compared with that encountered in other

parts of the United States.

KFPY CONTOUR MhP:

 

The field intensity pattern of KFPY'is shown in Fig. 530" As
measurements were made only on four radials, these contours can
be said to be accurate only in the region near the radials. is
has been mentioned before the main purpose of this survey was to
determine attenuation factors for each radial and for this purpose
the survey was entirely satisfactory.

Although numerous local shadows appear in the field intensity
vs. distance curves, the general contours show no great irregular-
ities with the exception of an elongation to the south. This is
probably caused by two things, namely, less attenuation to the
south and less initial absorption from buildings near the antenna.

The soil in the Spokane territory is a variation of gravelly
loam and basaltic rock. With the exception of the Spokane Valley,
the nature of the terrain is generally mountainous to the north
and east. West and south the rocky, broken terrain gradually
merges into the rolling hills of the Big Bend and Palouse wheat
country. There is no reason to expect that attenuation to the
west would be much different than to the south and indeed an ex—
amination of the curves for attenuation factor indicate that there
is not much difference. The Davenport Hotel and the towers and
antenna of KHQ are directly in line with the west radial and
probably account for much initial absorption of energy in this

direction.

FIELD INTENSITY SURVEY
KFPY- SPOKANE, WASH/N670”
I340KC. I000 WATTS

MAY 13-23 133.3
DWKamyay'Rammntwv

 

 

DAVENPORT‘

 

 

 

 

 

REAROAH

S'mimcoaLE

 

 

 

 

, Loon LAKE

 

' om mm

waysmE

 

(on,

(DAWN-'01")

 

 

 

 

Deep cREEK

 

 

 

 

 

 

 

 

 

 

HORTH pmt‘. .

STEET°E
5. suite

 

 

SPOKE" '.

BRIDGE.

coeun d'ALeue

 

 

 

N

 

\w .

 

 

 

 

 

 

 

 

 

 

 

' 1.—

-150-

ESTS FOR LOCATION:

 

Another use to which a field intensity meter may be put is
exemplified in Figs. 53, 54, 55 and 56. It was desired to deter-
mine if there was in the neighborhood of Butte a better location
for a transmitter than that used.

In order to run this test on 1360 kc. it was necessary to
make these tests at night after the commercial transmitters of
KGIR and KGER were off the air. This allowed six hours between
1:00 a.m. and 7:00 a.m. for a test. The necessary authority to
use a test oscillator during these hours was obtained from the
Federal Radio Commission.

A tuned grid tuned plate oscillator of low power was built
up in bread board style. This was installed in a car with the
necessary batteries and a frequency meter to check the oscillator
tuning. A portable L type antenna was built up so it could be
strapped to the side of the car and easily transported to each of
the desired locations.

A preliminary survey had disclosed four locations which were
available from.the standpoint of easy access, cost of lease or
ownership, power and telephone facilities, water supply and suit-
able space for antenna construction. It remained now to determine
which location was the best from a transmitting standpoint.

Location #1 was on a flat near Silver Bow Creek some eight
miles west of Butte. The soil here is more of a loam than any of
the other locations and there are no hills of importance within a
radius of several miles. The antenna was set up in a north-south

plane. The oscillator was tuned to 1560 kc. and the antenna

-151-

coupling adjusted for'maximum.radiation. Care was taken to keep
the antenna current constant throughout the test. In all these
tests the input power was adjusted to give the same field intensity
reading at .6 mile in the same direction from the antenna and the
antenna was set up in a similar position each time.

Measurements were taken in five directions from the trans-
mitter. One direction was not strictly a radial as may be seen
from Fig. 53, but measurements taken along this road south of
Butte gave points in a radial direction from the transmitter.

The next night, the antenna was set up on a hill directly
north of Butte. This hill overlooked Butte and all the country
to the east, south and west. Measurements were made on several
winding radials as shown in Fig. 54. The soil at this location
was dry decomposed granite.

Location #5 was on a flat south of Butte along a widening of
Silver Bow Creek. The soil here was damp and sandy loam. Con-
siderable grass and small vegetation was present along the creek.
As there was considerable unfenced area south and west, it was
possible to make measurements on direct radials in these direc-
tions. The east radial was necessarily short because there was
no pass over the Divide in this direction. The longest radial
made on this test was up over the Divide toward Elk Park and Helena.

The last test was made at a location known as Mammy's Shack,
a former road house about six miles west of Butte. The soil here
was similar to that at #l, but the whole area was much more moist
from seepage from a small creek. As initial measurements seemed

to show less attenuation, we were encouraged to carry this test

—l52-

out to a greater extent than the rest. As may be seen from
56, the pattern is much more regular than the previous tests. The
only irregularity is noted to the northwest. This is evidently
caused by a series of hills about a mile from the location. Spot
measurements taken behind these hills were the basis for showing
this shadow. However, this shows signs of healing and filling in
on the outer contours, due to energy feeding in from the portions
of the wave front on either side of the hill. It is evident that
a transmitter in this location would cover Butte in a satisfactory
manner and would probably extend a usable signal into Helena to

the northeast and Dillon to the south. While Deer Lodge lies in

\.

ct

he direction of the shadow, it is probable that the shadow would

0‘

e dissipated at that distance.

Location f2 shows severe attenuation to the northwest and a
deep shadow to the south which is undoubtedly caused by the city
of Butte. #5 shows severe attenuation to the south which is hard
to explain except on the basis that the soil here is dry decomposed
granite and rock. As a usual thing a radio wave will form better
with the transmitter in a valley than on a hill. Examination of
}2 ant $3 shows this to be so in this case.

#1 is the second best location but was decided against in com—
parison with #4 because of the slightly better field pattern of
the latter and also because of greater accessibility.

These four tests show the value of field intensity tests for
location. Installation of a radio transmitter and antenna usually
involves great eXpense and a small amount spent in previous test-
ing may eventually save the station owners several thousand dollars.

KGIR are planning on moving their transmitter to test location #4

in the near future.

 

 

 

 

 

F'G.53

 

Lgcg‘rlgu TESJ' no;

Lnn,ht

 

 

INN I

. 2, o . a 3 4 >MIIC$

.—r - - - . . I

x ,1

FIELD IHTEHSITY PATTERn OF TRANSMITTER
LOC-I‘W'Eo AT SILVER BOWJ'

 

 

 

 

 

GRECSON

 

A

 

v'o‘)’
'

3t
\ - ‘ .-
Fulzv ‘ if,
I ,x‘
‘ scALe. 99: I
'fLH—L—Ha rm LE:

 

*TEST LOCATIOH a 2

F_IELD H
[2.6.54 I TEHSITY PATTERN OF TEST

mAHSMITTER on HILL NORTH OF BUTTE

 

 

 

 

 

 

  

TEST LOCATION #3

FIELD INTENSITV PATTERN 0F TEST TRANSMITTER
LOCATED on FLAT SOUTH OF BUTTE

 

\

/ ax. \ \
n: '
a ‘ . I

. ’

601' -- I
l I

'-

~/

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TEbT LOCATION #4

Fists

new INTENSITY PATTERN or rest
Twamnrsa AT MAMMY'S 5HACK

 

 

 

 

 

T III III! LII

in! I!

 

0
~

Chapter 3 x
ATTEITUMION or GROUND .1
Dr. Dellinger has shown in his classical proof that the for-

mula for the magnetic field intensity at any point from a vertical

grounded antenna is

Ht:%o%$ eosw(t-%-) -'I;Io Smw(t-%_)

where instantaneous value of magnetic field intensity

H
h = height of aerial
w

ZTT'F

c = velocity of electric waves = 5 x 1010 cm. per sec.

d - distance from sending aerial
t - time
- maximum value of current

The second term represents the induction field and is negli—
9

N

gible beyond short distances due to the invers d term. The
first term represents the radiation field which is useful in pro-
ducing a signal at a considerable distance from the antenna and
is the one which is cons'dered in field intensity me-surencnts.

The effective magnetic intensity is expr seed by he term

*1 ZTFf:h]L
Iced.
effective current.

 

where I

Replacing n by its value a = E, and simplifying: the formula,

as
we have
5 =eorrhlf
ed.

for the electric field laid down at distance d by a simple ver-

tical grounded antenna.

-lSd-

For a 100p antenna this formula becomes

8. =lzorthF
ed. *

In field intensity work this latter formula is the one used
in computing conditions at an ordinary transmitting antenna based
Upon field intensities m,asured by a 100p receiving antenna.

This formula more commonly appears in the form

8:. 3'7"} hIF
ed.

Where to recapitulate,

6

h . effective height of transmitting antenna in meters

electrostatic field intensity in microvolts per meter

I - effective antenna current in anperes
f - frequency in kilocycles

d - distance in kilometers

0 velocity of electromagnetic waves in meters.

In terms of wave length this formula is

a: 3"" h]:
/\d
Where f\ = wave length in meters.

The early experimental work of Duddell and .aylor, and
Tissot indicated that the intensity of the received signal fell
off more rapidly than would be expected from a decrease due to
simple spreading out of the energy. This indicated a loss from

absorption of energy by the surface over which the wave passld.

‘ L" "a r U --r 'ir—TT ’-
§LIJTKJTLLI_(JOILIJL; .L‘OA.L-~-U f.

 

Dr. Austin was the first to perform experiments from which
an empirical formula for this absorption factor could be derived.
The equipment used in these tests has previously been described.

In these tests, Dr. Austin did not consider the electrostatic
field, but derived his formula in terms of the “eceived antenna
current. From Duddell and Taylor's experiments it was assumed
that the received current would be inversely preportional to the
distance with no absorption. in inverse distance curve is shown
in Fig. 57. From a curve of this nature and ones plotted from

the eXperiments at Brandt Rock, a formula was derived which ap-

peared in its first form as

IR ... _§_e—Ad

Where K _ received current at unit distance

A a constant

IR : received current at distance d.

Dr. Louis Cohen of the National Signaling Co. then discovered
that
/\ :: 32;.
'f\
where B. = coefficient of absorption.
From these early tests 2» was found to equal 0.0015 for trans-

mission over sea water.

The final formula derived from these tests was
IR = 4.25 h.h3 6,—0.00254.
fixci

Where IR = received antenna current

h] a sending antenna height

 

h;j receiver antenna height

e base of natural logarithms

fi\and d are in kilometers.
This formula remained unquestioned for many years until la-
ter tests by Vallauri and further tests by Dr. Austin caused a
revision in which the formula was given in terms of electrostatic

field intensity. This later formula is given as

2M3. 12233 3
{a l\dt Suva e? 4&°" ' '0

Where 9 angle at earth's center intercepted by transmission

path, in radians
I - effective transmitter antenna current
h : effective transmitter antenna height.
This formula holds with good accuracy over surface for which it

was intended; namely sea water.

)
For usual field intensity measurements where the angle

is so small that Slflez e the term lg?“ can be neglected.
From the above an attenuation factor can be defined as a

factor wl'lich when applied to the term 3'” hI— will give the

l\cL

field intensity at a distance d.

KENNECK'S FCRKD l

J. Zenneck has deveIOped a theoretical formula based upon
wave propagation over an earth of infinitely great conductivity

and surrounded by a homogeneous non-conducting atmosphere. In

this he shows that the amplitude of the electrostatic field:

-l57-

E0 : [2.0 TT 94b... Io amp YOLTS
A A. c.m ens

Where IO 3 current amplitude at the current antinode of the antenna
h = height of antenna
a = antenna form factor
r = distance from antenna

The term ah will be recognized as the effective height used in
Austin's and Dellinger's formulas.

In computing field intensities at great distances, Zennech
introduces a correction factor taking into consideration the cur-
vature of the earth and shows that the amplitude is preportional
to 'fi;’ éifi; which term also appears in the corrected Austin
formula. However, Zenneck shows curves which indicate that due
to converging meridians between 90 degrees and 180 degrees around
the earth's surface the amplitude should increase. He accounts
for the failure of the amplitude to increase to a straying of
some of the energy into Space rather than following the earth's

surface. He shows this stray energy coefficient to be equal to

- 0.00l9 h,

an?

and the variation in amplitude A over the curved surface of the

63

earth under the condition of infinite conductivity and finite

dielectric constant stated above to be

: o -oxnnslu
/\ F\°'*C Enact c: EEEET_“

This formula evidently is of importance only at distances compa-

rable to 1/4 quadrant of the earth's surface.-

l“ a
- .../1:)—

Under these conditions Zenneck shows the electric component
of the wave to be a purely alternatin: field perpendicular to
the earth and to the flow of energy and in phase with the magnetic
component.

However, under conditions of a surface of low conductivity
the electric field tends to follow the direction of travel of
the wave and becomes tilted; that is to say, a horizontal compon—
ent is introduced. This horizontal component sets up convection
currents in the surface viich causes a falling off in wave am-
plitude. (This wave tilt is the basis for the design of the Bev-
erage wave type antenna which is used so successfully in the
United States.)

In a general formula Zenneck shows that taking attenuation

into consideration, the amplitude of the electrostatic component

Eio Z IZCVITO'In SEE. <3'"E5h’
X IL
This formula is similar to Austin's with the exception that
. . , . , I
in the case of a ground of high conductiv1ty such as sea water 7::
.L.

appears in the .fl term and A appears for ground of low conduc-

tivity such as dry soil.

-159—

SOKKERFELD'S FORMULA AND ROLF's GRuPHS.

In 1909 Sommerfeld published a paper, "The Prepagation of
Waves in Wireless Talegraphy," in which he presented a very com-
plex analysis of the factors affecting the field intensity of a
radio wave at a distance from a transmitter. In this exhaustive
article he derives a theoretical formula which includes five in—
dependent variables for each of the two bounding surfaces between
which the wave travels; viz, air and earth. These variables are
as follows: conductivity 6. and, 62 , inductivity or dielectric
constant 6,.de 5,2 , permeability 44,,de “,2, wave length A
and distance r.

This formula is in the form.of an asymptotic series and is
not a very practical one for computing the field intensity. For
this reason it had not attracted a great deal of attention until
1929 when Dr. Bruno Rolf published a set of graphs based upon
the Sommerfeld theory and designed for the practical use of the
engineer. This set of graphs appeared in the March, 1930, issue
of the Proceedings of the Institute of Radio Engineers and lately
has been the subject of much trial and discussion.

The original formula of Sommerfeld differs from those of
Austin and Zenneck only in the attenuation factor which appears
as a complex integral in terms of the five independent variables
previously given. This complex symbol appears in the form eg— fiqib
where the term.%q is called the numerical distance and b is an
angle varying between 0 and 90 degrees for the ground wave. The
angle b determines the shape of the attenuation curve, while the

numerical distance %q determines the scale.

 

—160—

By mating certain assumptions, Rolf has written equations for
q and b in terms of four variables, 6 , E, , A and r. lLis assumed

as one, its value in vacuum. These equations'are

b'AH.b fill.
G>A.é>-Io'5'

[I

 

_ aTrsm b A,
Cb - 6+! 7:—

In his graphs, Rolf has plotted the attenuation factor as
ordinate against q, or Sommerfeld's numerical distance doubled
as abcissa. The attenuation factor appears in the form
where both u and v are shown to be dependent upon q and b in a
complex series equation. From these equations Rolf has computed
values of attenuation factor and numerical distance for values
of b from O to 90 degrees. A family of these curves is shown in
Fig. 58.

To use these graphs the following procedure must be observed.
It is assumed that field intensity measurements have been made
on one frequency. On logarithmic tracing paper of the same size
and number of cycles as that on which the Rolf’s graphs appear,
plot the measured values of field intensity multiplied by the
distance as ordinate against distance as abcissa. It way be neces—
sary to smooth out local shadows from.these curves with a dotted
line. Draw a vertical line at a distance corresponding to 100 wave
lengths. Care should be taken to compute the distance in miles
if miles have been used as a unit in computing theEd curves.
Draw a horizontal line at the ordinate corresponding to the dipole

moment of the transmitter. This is the field intensity at a unit

 

 

 

 
  
    
    
  

REFERENCE- LINE5 FOR DIST/wife o'r': IOO WAVELENGTHS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

WHEN§=§g60504o 30,}; .-'I5 I0 7 55.5..11
} L:.’-f-..::-- ..“rw ' - ;
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1’313112. .. L
.42-53" ...............
lot.” .....................
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[:1

T I 2 : ‘\
RlTl-IMIC 501: or DISTANCES TO BE PAS o II£II£23 ~.=}§.x

\
t. On. I.“ (NUMB

- or WAVE°LENGTHS) ,, . “35‘

\

   
 

F1C1.58_

-l€l-

distance from the transmitter where no attenuation is assumed to
exist. If the effective height is known, this can be computed
from the familiar 377 hi formula. However, it is usually deter-
mined from the measured\field a few wave lengths from the antenna.
Place this tracing paper upon the Rolf's graphs so that the ver-
tical line representing 100 wave lengths coincides with one of
the vertical lines for different values of 8 and the horizontal
line falls on the line marked 1. The value of 6.15 usually be-
tween 10 and 20 for land. Shift the tracing paper around between
these values until the graph which best fits the Ed curve is
found. Note the value of b on this graph and the value of 6 used.
Ed curves for measured values of field intensity of KFPY in
two directions are shown in Fig. 59. South and east measurements
were taken because these represented the limits of attenuation
found in this survey.

Having determined the value of €.and b, it is possible to

compute the conductivity CS from the formula

6 . |°|5 ._. (€*‘)(COT b)
GA

This value of 6 for the eastern radial turns out to be 23.8 .

-14
10 e.m.u. This is considerably lower than the average for the

—15 . . . .
United States, which is taken to be 10 e.m.u. The conductiv1ty

 

of the soil along he southern radial is very near the average,
as it is computed to be 1.16 . 10‘13. It will be noticed in de-
termining conductivity from the Rolf's graphs that the value ofne
does not affect the conductivity much over the broadcast range.

For instance, the Ed curve of the eastern radial may be made to

fit the curve for b = 22% degrees fairly well by using a value of

 

.NUT-(PPW.Q W) \ALLWCWLIT. .

QJW~u

I.1-u... ‘ D I

I-‘|

 

 

\ \\.~Iu\IfI. i

78910

6

 

 

 

MOI—I063“. tor-IfxD CWLILIKV‘

.w.||»\.. \I.\!I. \
.

 

 

FlG.6|

MILES

7
o.”

WOFO/‘u tau—LIARDZIW IPLIK‘

 

.. ..1..:...L...VA-»I~

..Ih. 2...!- oz .) .z .0 v IIU'-N .I ~l.|\\-qu

 

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pute
es
of

lengths

 

3a hori—
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wave
usly

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fig.
5 3 2 _,. the

2 ‘ marked

[.3 . ced.
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.30f

sities

 

; : nten-
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. . .uation

 

.encies
3 curves

1t

 

of

Upute
es
of
lengths
a hori-
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usly
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the
marked
ced.
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Inten-
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.uation

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.L ....I. v H. .. .....: .u... “A. ~—
J.I.N.I\-)fi .32 .F .2 ...1.”. IMHWU 4 JLLL:LX

pencies
curves

 

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III.

~162-

. . -14
E I 15. The final computation then comes out 2.9 . lO .

It is possible to predict attenuation curves for a band of

frequencies in the following nmnner. From the formula

 

AK” ._._ (€+l)(COT b)
6 <5 - Io '5

in which the same values 'of E, and CS are used as in (1'7) compute
the wave length for different degrees of b between the values
which cover the desired frequency range. On another sheet of
tracing paper draw vertical lines corresponding to 100 wave lengths
and mark each line with the proper value of b andx. Draw a hori—
zontal line rossing the vertical one. Now place this paper
over the graphs and let the vertical line representing 100 wave
lengths fall on the line representing the value of previously
determined. Trace the curve for the corresponding value of b.
Now slide the paper along until the next 1001‘ line falls on the
line and trace the b curve corresponding to the value of b marked
on this line. Repeat this until all desired curves are traced.
Figs. 60 and 61 show curves for the south and east radials of
the KFPY survey. It is now possible to predict field intensities
on any frequency over this path by knowing only the field inten-
sity close in to the transmitter. This is done by computing the
inverse distance value and then multiplying it by the attenuation
factor shown on the b curves for the distance in question.
Examples of such predicted field intensities for frequencies
of 590 and 890 are shown by the accompanying tables and the curves

of Figs. 62, 63, 64 and 65. These curves show the agreement

omnarisrh b th_fiflg _ .
. ’ theoreti al Valdesio‘If
.f “ intensit tpr d1dteh“fio
61 -~~a£id
assured [t
Dokane” ~~I

I
i
I

..I
i
Y

South‘ ~-
H .- ““* n

>x~1 ?I’

I
. I I l .
‘ . I
l
l

:Iheoretica

-+.—.. ...

Millivolts per meter

 

 

‘ 2 3 4 5 6 78910 2 3 4 5 6 7391u 2 3 4 s 6 75910

Miles

FIG. 62

Millivolts per meter.

7

8910

Miles
FIG.63

7

i"!
l

. n. 9: betree

theoretic l refines,»

intensity predicted;
' ‘i ' ' ndé
suréd ‘ields”ih

4...._.-_- . I. -

I . . , I
T O - O b 0 - I I I l v i 0 - { . I
. . . . . i . .

i
t 9 b O D . c I
I
l

 

8910 2 3 4

f

f
t

O

k

 

6

—A-

75910

 

.hmpoa hon muHo>ufldwi

Miles

FIG.64.

krpr

S

‘d.tho

ig a_hs

3%

n'othe
.'.,l

. . --- .—.—a-

'0

o’r1

-_¢_...

'ne sureme

I
‘I
f

6

.. diar‘

”S u

h.
.I¢..
_
.
...
—
v‘
_
_
.a»

 

78910

6

8910

7

8910

7

Miles

FIG.65

Millivolts per meter.

5‘i45 “ * " T'i ' f: L'M", .. ' T i ,
. 1 I -- - - H I I ;

Cdm risen f:field int as
predict—€35 ffiééfb -. I
igraphSTand;those'predc e !-
'"" ements- y.
her 're u n i

.-.“ .

._- ---. .

5.

PO
‘ ‘ ;_.___-.'.il--

“on o

I
,4.I‘

'Leadial .f
.. .i

—
‘4 CO .00

(.‘5

(F

 

R)

0‘le00

 

78910 675910

Miles

FIG.G4.

flfi
my

égna Es
yfib

.t_

i
'66

s”m
‘fre ue c e

d;thb
sfi?§fié‘
n'Othe

5 4

.pmumfi pmm

mu HO>fiHHHS

 

78910

6

8910

T

8910

7

Miles

FIG.65

-163-

between predicted values and actually measured values on the
590 kc. frequency and also show the agreement between values
predicted on 890 kc. from Rolf's graphs and values predicted
from attenuation factors derived from actual measurements. It
will be noticed that the agreement is fairly good, the values
obtained by Rolf's graphs being hicher in either case.

Van der Pol has treated the Sommerfeld theory in a little
different manner. He shows the formula in the form

E; ; 5.3'ITS— 3(F7
0|

in which E _ field strength in millivolts per meter

doublet antenna power in watts

P
d

distance in miles

y'(P) - Sommerfeld's integral.
By making certain assumptions he derived an empirical for-

mula for this integral which appears in the following form:

 

(p) : 2-+.3»P
3 2 1- P+.GP’-
in which F = 838+ 'o‘md— -_- Sormerfeld's numerical distance.

 

A26

COLE? U'I'JL'D DATA FOR U313 11‘ 1TH 30 LF ' S GREEHS .

<5. 10'5 :_(E.+I)(C.OT b}
6 /\

5:10 /\=.224 Kn. b :IG’ 6: 2.8 . 10"”

 

AK” : (6+!)(co1'b)
6 6-Io'5

EAST RADIAL

 

 

 

b /\ km 100 A, miles
1 3.747 353

3 1.873 115

5 .738 46

7 20' -508 31.5
10 I .371 33
11 .337 20.9
16 .224 13.9
20 .179 11

30 .113 7

 

 

 

~165-

COIIPUTED DATA FOR USE TJITH ROLF 'S GRAPHS.

6 . .015 :LE-H) (COTD)
6/\

 

 

 

 

 

5: IO /\=.224 KM. b=4° 6" “(Odo-.3
AKH = (€+I)(C.0Tb)
6 c5 - Io-G'
SOUTH RADIAL

b A km 100A,miles

1 .905 56

l 45' .508 31.5

2 .453 28

23 40' .337 20.9

4 .224; 13.9

5 .1806 11.2
10 .0896 5.5

 

 

 

—166-

COKPUTED FIELD INTSHSITIES FOR KHQ - 590 kilocycles.

EAST RADIAL

 

 

 

377 Q; d miles Rolf attenu- E
d ation factor
230 l l 230
46 5 .88 40.5
23 10 .71 16.3
10 23 .43 4.3 '
7.67 30 .32 2.45

 

SOUTH RADIAL

230 1 l 230
46 5 .98 45
23 10 .95 21.9
10 23 .8 8

7.67 30 .74 5.68

 

 

 

 

COMPUTED FIELD INT

”' "TC

.lLlN u.)

-167—

ITIES FOR KFPY - 890 kilocycles.

EAST RADIAL

 

 

 

 

 

 

 

377 Q; d miles Rolf attenu- E
d ation factor
87 1 l 87
17.4 5 .7 12.18
8.7 10 .45 3.74
4.55 20 .17 .74
2.9 50 .09 .26
S OUTH RA D111 L
95 1 1 95
19 5 .92 17.48
9.5 10 .8 7.6
4.75 20 .62 2.95
5.17 50 .48 1.52

 

~168-

SOME F NDINGS OF THE FEDERAL RADIO COMKISSION AND THE C. C. I. R.

ON ATTEI‘Wi‘iTION .

The Federal Radio Commission was formally organized on March
15, 1927, under provisions of the Radio Act of 1927. At this time
there were 752 broadcasting stations in the United States Opera-
ting on 89 channels. Due to the promiscuous frequency changing
indulged in by many stations after the courts had ruled that the

Department of Commerce had no authority to refuse licenses to any

 

station, these 752 stations were spaced throughout the broad—
.casting spectrum.with no great thought being given to interference
between stations. It became the duty of the Federal Radio Com-
mission to bring order out of this chaos and to evolve a more or
less permanent system of frequency and power allocation. The
development of such a system.has been a slow and tedious process
and it cannot as yet be said to have arrived at a state of perma-
nency. However, much progress has been made and although the
system is constantly changing to keep pace with increased know-
ledge of the art of broadcasting and other phases of radio trans-
mission, certain fundamental concepts upon which the present
system is based have remained unchanged.

While a radio station can not be said to be a public utility,
the facilities it uses such as frequency and power, do come under
that heading insomuch as they affect the listener. The term
"public interest, convenience and necessity" which is used by the
licensing authority definitely places the rights of the listener

before that of the broadcaster. To this end the Radio Act of 1927 ‘

-169-

provides that the United States be divided into five zones accord—
ing to population, and the Davis Amendment to the act further pro-
vides that each zone shall have an equal allocation of broadcast
licenses, of bands of frequencies, of periods of time of Operation
and of station power, and it also provides that the states within
each zone shall have equal facilities according to their popula—
tion.

This preportion of broadcast facilities, being fixed by law,
became the primary basis for the allocation system. By 1928 the
number of broadcasting stations in the United States had been re-
duced to about six hundred and they were assigned to three dif-
ferent classes of service according to the Commission's general
order #40 adopted in August, 1928. These three classes were listed
as Clear, Regional and Local Channel Stations. The total stations
in the United States were divided in these three classes as follows:

40 night stations on clear channels, each 5 KW or more.
150 night stations on regional channels, each 500 to 1000 W.
150 night stations on local channels, each 100 w or less.

In this table, stations dividing time on one assignment were
listed as one station. Day stations and limited time stations
were not listed. The types of stations listed were assigned to
the different zones by a quota system which showed the ratio of
the number of full time station assignments of each class due each
state to the total number of full time stations licensed.

This quota system was revised in 1950 to a better unit quota
system in which the total available units numbered 400. This

allowed each zone 80 units.

 

-170-

In order to make assiCnments according to this basic plan with
the least amount of interference, empirical standards were derived
by the engineering section of the Commission. These standards were
first arrived at from a close study of the mass of field intensity
data gathered by the field force of the Radio Division, Department
of Commerce, evidence submitted by other engineers at Commission
hearings, from many theoretical field intensity formulas and from
work of Commission engineers. These empirical standards have been

changed from time to time as more complete data has been furnished.

 

The prOper allocation of broadcast frequencies is at best a
complex problem for the reason that radio waves recognize no set
boundaries. They spread out everywhere and may cause interference
where least expected. The results of many thousands of observa—
tions may vary over a considerable range, which makes an average
of these observations liable to wide error. he definite limita-
tion of the number of available channels also makes the problem
more difficult.

Some of the considerations affecting these standards are the
(l) sensitivity and selectivity of the average receiving set, (2)
ratio of field intensities necessary to avoid interference on chan-
nels of different degrees of separation, (5) the field intensity
requirements for different classes of service, (4) the relation of
service to nuisance area, (5) location of stations in pepulous
areas, (6) the preper ratio of day and night time power, and (7)
the effect of different conditions of frequency, terrain and an-
tenna design upon radio transmission.

A channel separation of 10 kilocycles was early adOpted in 1

this country in order that there might be room between channels

-l7l-
for 5000 cycles audio sidebands above and below the carrier. The
problem of geographical separation of stations on adjacent chan-
nels became one of determining the necessary ratio of signal strenith
of wanted to unwanted signal based upon average receiver con—
stants and knowledge of carrier transmission.

In 1929 the mean sensitivity of commercial receiving sets
ranged from 10 to 1000 microvolts and the mean selectivity at the
center of the broadcast band of frequencies was within the range
of from 20 db to 50 db down at 10 kc. separation from the desired
signal. Present day receivers of good audio frequency fidelity
have not changed a great deal in selectivity, but in many of the
better sets the sensitivity is below 4 microvolts. In many
sections this is below the noise level, but in communities where
the noise level is low this increased sensitivity has the effect
of changing standards of reception. Fig. 66 shows the standard
curves depicting the interference spectrum as determined by the
Commission engineers both from the standpoint of the average and
the highly selective receiver. The following table shows the neces—
sary ratio of desired to undesired signal in the broadcast band

based upon the interference Spectrum.

 

 

Type of Operation Ratio of desired to
undesired signal.
Synchronous operation 4—l
Lhtched frequency Operation (maximum
deviation 5 cycles) 10—1
50 cycles maximum deviation . 20-1
10 kc. difference in frequency 5-1 to 0.900 to l
20 kc. difference in frequency l-l to 0.200 to 1
50 kc. difference in frequency 0.25-1 to 0.090 to l

40 kc. difference in frequency 0.085-1 to 0.055 to l

900
000

700
000

500

400

300

200

IOO

80
70
60
SO
4 O

30

20

I907 05 4

3

IO
0.0

0.7

0..

0.5

0.4

0.3

2
a

0|

0.07
0.“
0 as

0.04

0.03

0.03

 

0.0l

40

(Fun 9- m)

30

IO

20 IO

30

mas—31

than“.

~172-

In 192 a signal intensity of at least 10 millivolts per mete
was thought necessary to give satisfactory service. This s,andard
of minimum signal level has been gradually decreased with the in-
crease in receiver sensitivity and with the accummulation of field
intensity data. The present standards of good service are divided
into three classes, depending upon the noise level. These stand-

ards are as follows:

 

 

Area - Necessary signal intensity
Business section of cities 10 to 25 mv/m
Residential section of cities 2 to 5 mv/m
Rural section .1 to 5 mv/m

 

Another unfortunate fact tending to increase the difficulties
contingent with station allocation is the wide difference existing
between the interference or "nuisance" area and the service area.
The "nuisance" area is defined as the area in which the station
may cause interference to another station operating on the same
frequency. The service area is defined as the area free from in-
terference 90% of the time. This area is empirically defined in

terms of millivolts per meter field as follows:

 

 

Class of Station Boundary Service
Power Day Night
Watts mv/m. mv/m
Local ‘ 100 2 2
Regional 250-1000 .5 1
High Power Regional 5000-10000 .5 1

Dominant Clear 5000-50000 .1 .5

~173-

The Commission terms the area enclosed by a field of this in-
tensity as the protection area a d guarantees protection from in-
terference within this field.

Fig. 67 shows curves of allocation factor vs. nuisance dis-
tance in miles. These curves have been develOped by the Comm’ssicn
from a study of available information and when applied to the curves
of interference spectrum.in Fig. 66 and curves of average field
intensity form the basis for a table of average separation between

broadcast stations. A sample of this table for l kilowatt night

time separation is reproduced here. Complete tables for all powers

 

and for both night and day time separation are given in the Seventh
Annual Report of the Federal Radio Commission. These tables are
calculated to minimize objectionable interference in the good ser-
vice areas of stations about 90% of the time.

INTERNATIONAL RADIO CONFERiNCES:

The international character of radio has been the cause for
calling international radio conferences from time to time and for
the creation of committees for the study of radio wave prOpaga-
tion and to make recommendations for international frequency allo-
cations.

In l912 many of the nations of the earth were signatory to
the London Convention Which provided for an international clearing
house of radio information known as the Berne Bureau, which was
located at Berne, Switzerland. In this treaty certain frequency
bands were assigned to each country for certain specific purposes
and the licensing authorities of each country looked after the
assignment within these bands.

The last international radio conference was held at Kadrid,

~174—
Sp pain, from September to Uecember, 1953. it this con erence the
Technical Commit‘ee presented a condensed statement with charts
showing the average characteristics of radio wave propagation with-
in the range of 150 kc. to 2000 kc. Two of these curves are re-
produced here showing average characteristics for 550 kc. and 1500
kc. over land, these being the extremes of the U. S. broadcast band
-15

of frequencies. These are given for a ground conductivity of 10
which is considered averag e. In the Unite States the average con—
ductivity is someWhat below this and in Europe somewhat above.
Characteristics for other frequencies and for transmission over both
sea and land are given in the Proceedings of the Institute of Radio
Engineers for July, 1955. It is emphasized in this article that the
actual values may range from one—half to twice the averase values
depending upon differences in terrain and antenna design.

In July, 1955, the North American Radio Conference was held in
Mexico City. The purpose of this conference was to better the bro

sting conditions between Car ada, Hexico and the United States.

The U. S. delegates to this conference submitted a very comprehen-
sive report showing averafe transmission characteristics within the
frequency range of 150 to 1700 kc. and for distances up to 5000 km.
Two of these curves are shown here, one showing the ground wave for
six frequencies (150—500-550-1500-1700 kc.) a quasi maximum night
curve and an inverse distance curve, the other the ground wave for
these same frequencies at short distances. These were taken from
the Report of Committee on Radio Propagation ha a appearing in the
October, 1955, Proceedings of the Institute of Radio Engineers.
another interesting curve tal can from this report is shown in Fig. 72
in which noise level vs. frequency curves are plotted for New York

City.

I

O
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2:
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~175-

HUISANCE RADlus an Ml

sane Fneou e BCY

 

Table for Average Night Separation Between Broadcast Stations of

1000 Watts Power Based on a Frequency

Maintenance of _ 50 Cycles.

 

Frequency differential in cycles

Distance in miles

 

10
20
50
4O

 

 

1000
200
94
58
48

 

-176-

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-177-

 

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-179-

1 Put mzren

HINI‘H—UM 84- «0.200310 lass _
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FIGJZHOc SE. LEVEL vs FREQUENCY

 

Another very important international committee is the Inter-
national Technical Consulting Committee on Radio Communication,
more commonly referred to as the C. C. I. B. This committee was
established by the International Radio Telegraph Convention in
Washington in 1927. The first meeting was held in The Hague in
1929 and the second in Copenhagen in 1951. This meeting was atten-
ded by representatives of 58 governments and 58 operating companies.
The work of this committee has been a study of all problems con-
cerning radio communication and their recommendations have proven to
be of great value in arriving at standardized international radio

laws.

THE EFFECT OF ”NTEEIA DESIGU UPOL FI LD IN TLV‘ITY AT THE SOIL.

Until recently, antennas used at broadcast freQuencies were
generally a simple cozbina tion of vertical and flat top section
grounded at the lower end. These are commonly referred to as in-
verted L and T type antennas. The height of the vertical section
was generally less than one quarter wave length above the earth.

In an antenna of this type, the radiation from the vertical
portion is vertically polarized, while that from the flat tOp
portion is horizontally polarized. The horizontally polarized
wave is known as the sky wave because the energy of such a wave is
only prepagated at hirh angles with respect to the ea arth. This
energy may be detected on the earth at a considerable distance
from the transmitter due to refraction from the hennelly-heaviside
layer. Any horizontally polarized energy prepagated in a horizontal
direction is cancelled out within the area encompassed by the in—
duction field due to convection currents set up in the earth. 0n
the other hand, the vertically polarized wave known as the ground
wave is confined to areas close to the earth. The service area of
a broadcast station is determined by ground wave energy prepagated
in a direction horizontal to the surface of the earth.

The problem in the design of broadcast antennas, therefore,
becomes not only that of having a high ratio of total power rukl ted
to power input but also of obtaining a high ratio of energy prepa—
gated in a horizontal plane to the tot 11 radiated energy. The
former is known as the radiation efficiency and the latter CS an-

tenna efficiency.

~181-

DETERKINETION OF EFFECTIVE HEIGHT.

The radiation in a horizontal direction from an antenna de-
pends upon the current distribution in the vertical portion of the
antenna. The current distribution varies greatly for different
types of antennas. Antennas with long flat tOp in preportion to
vertical section may have almost uniform current in the vertical
section while an antenna with little or no flat tOp may have a
sinusoidal current distribution. The current distribution in some

antennas of different design is shown in Fig. 75.

F3H111CURRENT DWIHHHFWOH'N GROUNDFDKMHTENNAs.

 

In order to compare the rehative radiating qualities of each
type it is convenient to reduce each to an effective height. This
term effective height has been defined as that height in which the
current is the same throughout as that measured at a current loop,
with the radiated power remaining unchanged. Kathematically this

is expressed by the relation

1.
11e = ...1.. [IX (11: (4:9)
I o

where I = effective current measured at current loop

Ix

it

current at any point at distance x from ground

length of antenna

-.NQ—V' I

...-G -u a

 

O“)
— L)“ —

This cypression must be integrated over tie full length of
the antenna.
Experimentally, the effective height may best be determined

by measuring the field intensity at short distances from the

transmitter and computing the effective Peight from.the expression

a... 577 111 (so)

/\
the derivation of which appears in Chapter Six. A distance of be-
tween two and three wave lengths is the best for this purpose as
it is beyond the induction field and not far enough for ground at—
tenuation to have any great effect. Keasurements in a single di-
rection should not be relied upon for the determination of the
value of effective height, as this will give the value for that
one direction alone. There may be directional effects due to can—
cellation of energy or to shadowing and absorption from objects
within the field. A considerable number of measurements in dif—
ferent directions should be taken and the root mean square value
of field intensity at one mile should be used in the formula. For

example, for a one kilowatt station the following values of field

intensities may be found in four different directions:

mv/m Distance, Hiles
400 .35
360 .4
380 .3
460 .5

Reduced by the inverse distance method to millivolts per meter

at one mile, the following values are found respectively 140, 144,

114 and 158. The root mean square value is then 134.5 mv/m at one

-185-

mile which is the prOper value to use in the formula. In practise,
from 15 to 20 close-in measurements should be taken in order to

arrive at an accurate value of effective antenna height.

 

DETE MINATION OF RADIATION TESISTANCE.‘

Power in an antenna depends upon the equation
. 9

H

W = I R (51)
where R may be divided into three components as follows:
Hg a resistance of antenna wire and ground
Rd a resistance of dielectric surrounding the antenna

Rr = radiation resistance.

This last term is a fictitious resistance which corresponds to a
resistance which would cause the same loss as the power radiated.
It is the useful component of the antenna resistance. The first
two terms are often referred to as the dead loss resistance. The

power radiated is then expressed by the equation

U]
E\ I

"I 12 q (
”r = ‘r
where Rr is the radiation resistance

I is the effective current measured at a current loop.

According to Hund, the radiation energy from a dipole of length L

over a sphere of radius (9 is shown by the equation

2 2
tr = 2 p (51;) (5:5)
C

10
where c : 5 . lO cm/sec.

When 1 = Im sincnt, this becomes
2 2 2
szIm cos up 1: (54)

c—

"T
“r -

UHN

-le—

[‘0

 

From the equation ”r = I Rr then
K 2
Br = 33. 32:}: = 8772 Q (LL-)1 abohms == SDI-Tao?) Ohms (55)
3 c 3 ‘X

for radiation over the entire sphere. For half the sphere or the

part above ground

Rr =4OTT2(-§:)Z (56)

In all antenna formulas consideration is given to the fact
that the earth reflects energy. In other words, if the earth is
considered a perfect conductor there is an image antenna and there-

fore the L in equation (56) should be considered as equaling twice

the antenna height or L = 2h, and

RI» = IGOWa&—)z (57)

This formula only holds for uniform.antenna current so h must be
considered as the effective height. This formula often appears in

the form

 

a. = me; r— (.8,

here are available, then, three fundamental equations for use
in determining the effective height, radiation resistance and radi—
ated power of an antenna from close-in measurements of field inten—
sity at a known distance from the transmitter. From equation (50)
the effective height may be found. Substituting this value in
equation (58) the radiation resistance may be determined and knowing

I and Er the radiated power may be obtained from the formula hr =

2
I Br.

VERTICAL RADIATORS.

 

Although some ten years have passed since Stuart Ballentine

~185-

published his comprehensive articles with data and charts showing
the characteristics of vertical radiators, it has been only in
the last two years that this type of antenna has become extensive-
ly used in the broadcast field. About 1950, WABC in New York
became the first broadcast station to use a vertical radiator.
Since that time the pepularity of this type of radiator has in-
creased to such an extent that the older style inverted L and T
antennas swung between two towers are now considered obsolete.
Kechanical difficulties and high cost have propably been the main
reason for the long delay in the trend toward the vertical type
but these have been overcome to a great extent and now there are
many types of vertical radiators on the market ranging from self-
supporting quarter wave towers to center-guyed six-tenth wave
structures.

The efficiency curves of Ballentine are shown in Fig. 74.
Ballentine's original abcissa for these curves was ~%i; where >\
was the Operating wave length and 2N0 was equal to 4 L where L
was the height of antenna. In the reproduced curves the abcissa
is shown as the conventional antenna length in terms of fractional
wave length. These curves indicate that the most efficient ratio
of physical height to wave length for a vertical radiator is .64.
Above this ratio the efficiency falls off sharply and below this
value the efficiency falls off less rapidly to a point slightly
below .25 wave length where the curve flattens out and stays fairly
constant. Ballentine has also computed the radiation resistance

for the same values of antenna height. This curve appears on the

(cums)

V)
I.
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Q
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RADIATIOH neslsraucc

EFFICIENCY

 

Author's note-- Above curve should read Antenna E-ficiency

instead of Radiation Efficiency.

150°

160°

200°

210°

130°
190°

180°

190°

170°

210°

100°

150°

 

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same graph and indicates that the ratio giving the maximum radiation
resistance does not give the maximum power efficiency.

In Fig. 75 are diagrams showing the radiation distribution
from vertical antennas of different lengths as computed by Ballen-
tine. The shape of these diagrams depends in a complex way upon
the current distribution in the antenna and time retardations must
be taken into consideration. These diagrams show that for the
most efficient radiator (one in which the height is .64 wave length)
the radiation is mainly in a iorizontal direction. at this point
the radiation diagram splits into two loops with the smaller loop
showing the maximum radiation at a high angle with respect to the
ground. As the length of the antenna increases above .64, the
radiation at high angles is increased and the ground radiation is
decreased until at a certain value of height the ground radiation
disappears entirely as shown in Fig. 75c. The-diagram for a quar-
ter wave antenna approximates a semi—circle. These figures must
be considered as figures of revolution and to find the total power
radiated an equation must first be determined for each and inte—
grated over the whole diagram.

The Federal Radio Commission has made use of these diagrams
in determining the radiation patterns used as a basis of their
mileage separation tables. Fig. 76 shows an empirical standard
pattern for the average broadcast antenna found in practise. This
indicates a field intensity of 125 millivolts per meter at one
mile with 45% radiation efficiency and 22%% antenna efficiency for

one kilowatt input power to the antenna. The highest antenna

-187-

efficiency found in a considerable number of measurements of broad-
cast antennas was 57% while the average was only 5.7%. In order
to have a standard to which to compare all antennas, the Commission
have arbitrarily chosen a pattern which is better than any obtain-
able in practise. This standard pattern calls for an effective
field of 265 millivolts at one mile with 100% radiation efficiency
and one kilowatt radiated power. Based upon the radiation patterns,
the Commission use the following formulas for determining the radi—
ating characteristics of any antenna.

For total power radiated from an antenna in terms of the total
unattenuated field intensity

P1. -_- KAPZ

where Pr is the total radiated power in kilowatts passing through

area A

2

K is a constant = 2.65 x 10-

A is area through which the field passes measured in square
meters

F) is the vector field over the area A measured in.millivolts
per meter. -

ror antenna efficiency
Aeff = -——+r‘——-
0 x P

For antenna directivity

D g Em
F—
For equivalent power in any direction
2
P8-
125

where P is the power input to the antenna or the licensed power
determined by the direct method (measured antenna
resistance)

—183-

P is the equivalent radiated power in aiy direction in
kilowatts, which may be used directly in the mileage

separation tables

6

F is the effective field at one mile from the antenna in
the horizontal plane without attenuation measured in
millivolts per meter

Em is the field intensity in any direction from the antenna
at one mile without attenuation measured in millivolts
per meter.

The Report of the National Association of Broadcasters for
July 26, 1955, contains some very pertinent info*mation on antennas
which was prepared by J. C. Kchary, Chief Engineer of the NAB,
and T. A. H. Craven, a consulting engineer of Washington, D. C.
Two of the charts contained in the reports are shown here and are
self-explanatory. They show a value of field intensity of 170
millivolts per meter at one mile for a quarter wave vertical radi-
ator with one kilowatt input power to the antenna and a ten ohm
dead loss resistance (this is considered an average value). In
practise a correction factor should be applied to allow for atten—
uation in the first mile.

In a recent location survey on a frequency of 890 kc. in
Spokane, Washington, the author found that an attenuation factor
of .8 should be applied in the first mile for that territory.

Although Ballentine shows that, electrically, the most effici-
ent radiator is one with a height of .64 , it does not follow
that this height gives the greatest efficiency from a standpoint
of dollars and cents. From studies of the cost and efficiency of
various types of vertical antennas, it has been found that the
quarter wave radiator will give the most field strength for its

height; in other words, the antenna cost per square mile of service

VERTICAL ANTEMA cuamuemsms.
00 IGOHH LOSS '- W INPUT POWE'

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~189—

area is a minimum for the quarter wave type.

For a rough exeiple, the cost of a quarter wave vertical
t wer for a certain frequency was recently submitted as $5000,
while the cost of a .6 wave vertical center—guyed tower for the
same frequency was $12000. This is exclusive of installation

charges. The effective field intensity at one mile with no atten-

uation for a quarter wave vertical radiator with one kilowatt
input power is 170 mv/m, while that for the .6 wave vertical radi-
ator is approximately 265 mv/m. The ratio of cost is 4-1 while

the ratio of field intensity is approximately 2-1.

 

Due to the fact that the capacitance to ground is not uniform
in a vertical antenna the actual height does not correspond to
the electrical length. Py electrical length is meant the position
of the current vector on the antenna in degrees. For example,
he electrical length of a quarter wave antenna is 90 degrees.
In practise the tower would not be a quarter wave length in physi-

cal height but would be somewhat less. The actual length is

found by the formula
H = 9%
ft m
110

where e _ the electrical length in degrees

?\

There is little information regarding the preper ground system

wave length in meters

to use with the vertical antenna. In most cases this becomes an

individual problem. However, one type which has proved very suc-

 

cessful is one in which cepper wires are placed in radial direc-

tions from the antenna every 10 degrees and extending for one-

-190-

half wave length. This grounding system is most efficient when
placed on the ground, but for reasons of convenience the wires
are usually buried about six inches underground.

Referring to Fig. 75, the radiation in a horizontal plane
is seen to increase with an increase of antenna height up to .64 .
One great advantage resulting from this is that the increased
ratio of ground wave to sky wave pushes back the fading wall and
gives a greater primary coverage. Other advantaces of vertical

radiators are:

 

No tower absorption.

Less space required for antenna erection.
Reduced nuisance area.
More uniform distribution pattern.

For these reasons the vertical radiator is rapidly supplant-
ing the older types of antennas not only in the broadcas spec-
trum but also in the higher frequency bands such as are used by
police transmitters. The vertical radiator is especially effec-

tive in the ultra—high frequency range.

 

 

 

 

832*FOOt Vertical Radiator. WLW’CincinnatI,0hio.

.‘_A-_ :.5. on ,.

 

 

Chapter Eight
CONCLUSION.

In the preceding seven chapters of this thesis it has been
the aim of the armhor to combine the theoretical aspects of radio
field intensity measurements with practical considerations. In
order to give the preper background for the thesis, the first
chapter covered the general theory of radio prOpagation throughout
the useful part of the spectrum. This chapter is mostly refer-
ence work and it is realized that many names of importance in the
radio world were omitted. However, the field covered by this
chapter is so vast that the treatment is of a necessity very con-
densed and only the work of those who were pioneers in the partic-
ular phase of radio development described or of those who seemed
to be the most outstanding in their particular field was mentioned.
The author spent considerable time in reference reading before
writing this chapter and he believes it to be as truthful a pic-
ture of general conditions and as fair in the mention of those
engaged in research and engineering as can be expected in so con-
densed a work.

Beginning with the second chapter, the thesis has been limited
in its SCOpe to field intensity work, and this in turn, with the
exception of one or two historical cases, has been narrowed to
the confines of the broadcast spectrum as we know it in the United
States. Starting from here with historical mention of early
developments in field intensity measurements, the thesis hasgradu-
ally led into phases of the work with which the author is familiar

through actual contact.

 

~192-

In the chapter dealing with the description of various field
intensity measuring equipment, the equipment of two companies has
been described in more detail than others for the simple reason
that they are the only two companies having such equipment on the
commercial market. The author is also more familiar with this
equipment through actual operation in the field.

The fifth chapter might be said to be the climax of the thesis
insomuch as it represents work which has been done almost in its
entirety by the author and also because it really brings out the
importance of field intensity surveys from several angles. The
early survey on the Rochester station shows the difference in the
field intensity then thought necessary for good receptiOn to that
considered good in some sections today. For instance, the survey
on WHAM was only carried out to a signal level of three millivolts
and to a distance not greater than thirty miles for a five kilowatt
station, while the Butte survey was carried out to a signal level
of one hundred microvolts and to a distance of over sixty miles
for a one kilowatt station. In a recent survey on a five kilowatt
station made by Edwards and martin, the survey was carried out to
a distance of one hundred miles from the transmitter.

In the description of the survey of the group of stations in
the northwest, it was difficult to hold the work to that of a
statement of engineering facts and not give way to the impulse to
treat the case in a pOpular way, embellished with description of
the country over which the survey was made and to relate innumerable
amusing and some not so amusing incidents occuring during the

survey. It was easily the most interesting survey ever made by

—193—

the author and he will never think of Butte without experiencing
a mixture of emotions. The unpleasantness of cold fingers while
making measurements in a snowstorm on the Continental Divide, the
thrill of wild night rides on winding mountain roads in Ed Craney's
Buick while making interference checks, and last but not least,
the glorious sunrises viewed from some of the mountain peaks after
a hard night's work on location testing will be some of the last—
ing memories of that survey. l
The survey upon the group of Spokane stations was most impor-
tant in showing the difference in ground wave attenuation with .
different frequencies and in the sixth chapter this matter of ground g
wave attenuation is treated in a more extensive nanner both from
theoretical and practical considerations. Attenuation formulas of
Austin-Cohen, Zenneck, and Sommerfeld are discussed and the method
of determining ground conductivity by means of a set of Rolf's
graphs is shown.
In view of the great interest now being shown in antenna design,
a thesis of this nature would be incomplete without some mention
of the trend in this line. he seventh chapter deals with some
very important antenna formulas for use by the field intensity en~
gineer and there is also included a short discussion of vertical
radiators which are becoming so pepular in the broadcast field.
There is much research and experinentation being performed at
the present time upon antennas designed to radiate nothing but
energy in the horizontal plane. When this type of antenna is per-
fected, and there is much upon which to base the prediction that

it will become an eventuality, the wcrk of preper power and fre-

-194-

quency allocation will become much siwplified. It is predicted
that when such an antenna is made practical all broadcast stations
will be forced by law to install them and all stations will be
licensed on the basis of so many millivolts per meter in field
intensity at a predetermined distance from the transmitter.

In the line of transmitter development, the new 500 kilowatt
installation at WLW in Cincinnati with its 832 foot vertical radi-
ator which went into full Operation on may 2 of this year is the L
outstanding acconplishment in radio broadcasting.

much advancement has been made in the field of television
and it is now a foregone conclusion that tra emission in this field i
will be done on ultra-high frequencies and with vertical radiators.

There is much work to be done in the line of field intensity
measurements at high frequencies.

Although the author has encountered much hard work and many
disappointments in his line of chosen endeavor, the ever-changing
nature and the romance of radio have held his unflagging interest
and it is his earnest wish to continue to take part in these new

developments.

ACICNO ULED G—l‘xLilI‘TT .

The author wishes to thank Dean Ernst A. Bessey of the
Graduate School for his c00peration, and to especially thank
Professor L. S. Foltz and Mr. B. i. Osborn of the Electrical
Engineering Department for their helpful suggestions and
COOperation.

He is also indebted to Kr. I. R. Baker, Sales Kanager,
Transmitter Section, RCA Victor Company, Inc., for pictures
and information regarding RCA Victor equipment; to Kr. J. C.
Hchary, Chief Engineer of the National Association of Broad-
casters, for information concerning antenna design; and to
hr. 0. W. Edwards for pictures and for his constructive criti-
cism of this thesis.

He also wishes to thank Hr. E. B. Craney, Kanager of

K IR

Butte, Iontana, for the pictures taken on the survey of

)

that station.

BIB MIOGREPHY

Following articles taken from Proceedings of the Institute

of Radio Engineers:

1.

2.

13.

14.

measurements of the Height of the KennellyLHeaviside Layer.
G. W. Kenrick and_C. K. Jen. April, 1929.

A New Method of Determining Height of Kennelly-Heaviside Layer.
C. B. Mirick and E. R. Hentschel. June, 1929.

Further Notes on the Ionization in the Upper Atmosphere.
J. C. Schelleng. August, 1929.

Studies of Echo Signals.
A. H. Taylor and L. C. Young. September, 1929.

Group Velocity and Long Retardation of Radio Echoes.
G. Breit. September, 1929.

Further Studies of he Kennelly-Heaviside Layer by the Echo
Hethod.
G. Breit. September, 1929.

4otes on the Effect of Solar Disturbances on Transatlantic
{a dio Transmission.
C. I. Anderson. September, 1929.

T-
I

L
J.

Yireless Echoes of Long Delay.
P. O. Pedersen. 'October, 1929.

An Fcho Interference Hethod for the Study of Radio Wave Paths.
L. R. Kafsted and I. A. Tuve. October, 1939

On the Relation Between Long ”ave Reception and Certain
Terrestrial and Solar Phenomena.

T

A. Sreenivasan. October, 1929 .

The Si enificance of Observation of the Phase of Radio Schoes.
G. Lreit. October, 192

Further Observations of Radio Transmission and the Height
of the Tiernelly— Heaviside Layer.
G. W. Kenrick and C. K. Jen. November, 1929.

Report on Experiments with Electric Waves of About Three Heters.
Abraham Esau and Walter M. Hahnemann. March, 1930.

Summary of Progress in the Study of Radio Wave PrOpagation
Phenomena.
G. W. Kenrick and G. W. Picard. April, 1950.

 

17.

18.

19.

25.

Ultra Short faves for Limited Range Communication.
Y. J. Brown. July, 1950.

Wireless Telegraphy and the Ionization in the Upper Atmosphere.
E. 0. Hulburt. July, 1950.

Note on Skip Distance Effects of Super Frequencies.
A. Hoyt Taylor. January, 1951.

Kennelly-Heaviside Layer Studies. .
P. A. deflars, T. R. Gilliland and G. W. Kenrick. Janu-‘
ary, 1951. .

Kennelly-Heaviside Layer Height Observations for 4045 kc.
and 8650 kc.
T. R. Gilliland. January, 1951.

Radio Transmission Studies of the Upper Atmosphere.
J. P. Schafer and U. M. Goodall.

A kethod of Representing Radio Wave Propagation Conditions.
L. W. Austin. September, 1951. -

se of Automatic Recording Equipment in Radio Transmission
Research.
P. A. de Mars, G. W. Henrick and G. W. Picard. Sept., 1951.

A correlation of Long Wave Radio Field Intensity with Passage
of Storms. .
I. J. Wymore Shiel. September, 1951.

The Propagation of Short Radio Waves.
C. R. Burrows. September, 1951.

The Ionizing Effect of Meteors in Relation to Radio PrOpa-
gation.
A. M. Skellett. December, 1952.

Observations of Kennelly-Heaviside Layer Heights During the
Leonid Meteor Shower of November, 1951.
J. P. Schaeffer and U. M. Goodall. December, 1952.

Solar Activity and Radio Telegraphy.
L. W. Austin. February, 1952.

Investigation of Kennelly-Heaviside Layer Heights for Fre-
quencies between 1600 and 8650 Kilocycles per Second.
T. R. Gilliland, G. W. Kenrick and K. A. Norton.
February, 1952.

Kennelly-Heaviside Layer Studies Employing a Rapid Method
of Virtual Height Determination.
J. P. Schafer, W. M. Goodall. July, 1952.

30.

31.

32.

53.

54.

35.

36.

37.

38.

39.

40.

41.

43.

Transmission Characteristics of a Short Wave Telephone
Circuit.

R. K. Potter. April, 1930.

Application of Frequencies Above 30,000 kc. to Communi-
cation Problems.
Beverage, Peterson and Hansel. August, 1931.

Behavior of Earth Currents and Their Correlation with
Magnetic Disturbances and Radio Transmission.
Isabel S. Bemis. November, 1931.

A Study of the Prepagation of Wavelengths between Three
and Eight Meters.
L, F. Jones. Harch, 1933. s

Notes on Prepagation of Waves Below Ten Meters in Length.
Trevor and Carter. March, 1933.

Ultra Short Wave Propagation.
Schelleng, Burrows and Ferrell. March, 1933.

Some Results of a Study of Ultra Short Wave Transmission
Phenomena.
England, Crawford and Mumford. March, 1933.

The Use of Radio Field Intensities as a means of Rating
the Outputs of Radio Transmitters.
S. W. Edwards and J. E. Brown. I. R. E. Proceedings 16,
1173, 1193. September, 1928.

The Problems Centering about the Measurement of Field In-
tensities.
S. W. Edwards and J. E. Brown. I. R. E. Proceedings
17, 1377, 1384. August, 1929.

Graphs to Sommerfeld's Attenuation Formula.
Bruno Rolf. March, 1930.

Service Area of Broadcast Stations.
P. P. Eckersley. July, 1930.

Note on the Accuracy of Rolf's Graphs of Sommerfeld's
Attenuation Formula. -
W. Howard Wise. November, 1930.

Attenuation of Overland Radio Transmission in the Frequency
Range 1.5 to 3.5 megacycles per Second.
C. H. Anderson. October, 1933.

Field Intensity Keasurements at Frequencies from 285 to
5400 Kilocycles per Second.
S. S. Kirby and K. A. Norton. Hay, 1932.

 

44.

45.

46.

47.

48.

49.

50.

5]..

52.

55.

54.

55.

56.

57.

58.

On the Use of Field Intensity Keasurements for Determin-
ing Broadcast Station Coverage.
C. K. Jansky, Jr. and S. L. Bailey. January, 1932.

Investigation of the Attenuation of Electro—magnetic Waves
and the Distances Reached by Radio Stations in the Wave
Bands from 200 to 2000 Meters.

B. Fassbender, F. Eisner and G. {urlbaum. August, 1931.

Engineering Aspects of the Work of the Federal Radio Commission.
J. H. Dellinger. August, 1929.

Some Characteristics of Modern Radio Receivers and Their
Relation to Broadcast Regulation.
Lewis M. Hull. August, 1929.

The Regulation of Broadcasting Stations as a System Problem.
E. L. Nelson. August, 1929.

Some Principles of Broadcast Frequency Allocation.
L. E. Whittemore. August, 1929. '

A Study of Heterodyne Interference.
J. V. L. Hogan. August, 1929.

Basis Established by the Federal Radio Commission for the
Division of Radio Broadcast Facilities within the United States.
December, 1930.

Empirical Standards for Broadcast Allocation.
A. D. Ring. April, 1932.

Report of Committee on Radio Propagation Data.
October, 1933.

Second Meeting of the International Technical Consulting
Committee on Radio Communication, Cepenhagen, 1931.
December, 1931.

Recommendations of the International Technical Consulting
Committee on Radio Communication.
May, 1930.

The Hague Conference.
3. C. Hooper. May, 1930.

Low Frequency High Power Broadcasting as Applied to National
Coverage in the United States.
William H. Wenstrom. June, 1931.

Propagation of Waves of 150 to 2000 Kilocycles per Second at
Distances between 50 and 2000 Kilometers.
Balth Van der Pol, T. L. Eckersley, J. H. Dallinger and
P. Le Corbeiller. July, 1933.

. . ,. v.“

 

59.

60.

61.

64.

65.

66.

70.

71.

On the Radiation Resistance of a Simple Vert
at Wave Len3ths Below Vie Fundamental.
Stuart Ba llentine. December, 192 4.

On the Optimum Transmittinfi Wave Length for a Vertical An—

tenna Over Perfect Earth.
Stuart Ballentine. December, 1924.
Direct Ray Broadcast Transmission.
T. L. Eckersley. October, 1932.

\’ ' \‘r ' s' U ’ | s 1",- " ' \; '!\ “r '1 ' U a" s't ‘,- ' J ' <11! ! " ~ '
4**¥+*x4$xx$*$4ax+a*+axa*4¢%x4xsx<+Ax ¥+¥4$x
>'/\'~>' 9‘2).ng k‘ir:4r¥r~¢—*k,-"*,.1<4Y1<>Y4‘j>j<>kkwk>ifi<

Polarization of Echoes from Heaviside Layer.

ical

I ' | I l I I
\ J r \ a ‘ I I \< ‘ ’
fl" >5 fr '7‘ :A‘ 't ’2‘

L.

Antenna

fi0%*

T. L. Schersley. Nature - September 10, 1933.

Polarization of Wireless Echoes.

T1
p.

1927.

The EX mt ence of Kore than One Ionized
AtmOSphere.
E. V. Appleton. Nature, September 3,

Equivalent Heights of tlm Atmospheric Ionized

England and hierica.
E. V. Appleton. Nature, Harch 23, 19

Polarization of Radio Waves.

T\ T

E. V. Appleton and J. A. Ratcliffe. n

a

tn

7)
.L

e

1927.

)

Layer in the

1L8“: ii OHS

9.

Alexanderson. A.I.E.E. Journal, Vol. 45,

Short Wave Echoes and the Aurora Borealis.

Carl Stormer. Nature, ,

Short have Echoes and the Airora Borealis.
Balth Van der Pol. Nature, Decenmer

Propagation of Radio Haves Over Vie Earth.
Taylor and Hulburt. Physical Review,

Pr ropa getion of
31:11.11, 192'- 0

Radio Fading “Apelltenbo in 192

Dellinger, Jolliffe and Parkinson. Bureau of

dards Scientific Paper #561.

Electric Eaves Over the Earth.
Lichols and Schelleng. Bell System Technical

,1
‘2

27-189-1926.

November 3 1928.

page

1928.

in

Stan~

 

Journal,

72. Short Period Radio Fading.
T. Parkinson. Bureau of Standards Journal of Research.

73. Radio Observations of the Bureau of Standards during the
Solar Eclipse of August 31, 1932.
S. S. Kirby, L. V. Beckner, T. R. Gilliland, K. A.
Norton. Bureau of Standards Journal of Research,
RP 629, Decem er, 1933.
74. Radio Observations during Solar Eclipse of August 31, 1933.
Nature, September 10, 1933.

75. Night Effects in Range Beacon Reception.
H. Diamond. Bureau of Standards Journal of Research,
1933.

76. A Continuous Recorder of Radio Field Intensities.
K. A. Norton, 3. R. Rayner. Bureau of Standards
Journal of Research, September, 1933.

77. Some Quantitive Experiments in Long Distance Radio Telegraphy.
L. W. Austin. Bureau of Standards Bulletin 7-315-1911.

78. Principles of Radio Transmission and Reception with Antenna
and Coil Aerials.
J. H. Dellinger. Scientific Papers of Bureau of
Standards 8 334, 1919.

79. Electric Waves.
Encyclopaedia Brittanica, Vol. 8 - 14th Edition.

80. Radio Broadcast Coverage of City Areas.

Lloyd Bspenschied. A.I.E.m. Journal, November, 1926.

81. Bibliography on Radio Wave Phenomena and Measurement of
Radio Field Intensity.
Bureau of Standards — June, 1931.

83. Radio Transmission Characteristics of Ohio at Broadcast
Frequencies.
J. F. Byrne. Bulletin #71, Ohio State University
Studies - Engineering Series.

83. Seventh Annual Report of the Federal Radio Commission.

84. Report of National Association of Broadcasters.

85. Broadcast Antennas.
Hans Roder. Broadcast News, July, 1932.

86.

87.

Wireless Telegraphy.
jenneck.

Principles of Radio Communication.
Lorecroft.

High Frequency Kcasuremunts.
hund.

Radio Engineering.
Terman.

ADDENDUM.
Since starting this thesis the author has entered into the

commercial work of rield ;ntensity measurements. The field intensity

L-J

meter used is one of the atect type TMV 7a—B reCently developed

by the RCA Victor Company of Camden New Jersey. This meter is an
improved model having some of the better characteristics of the

RCA TMV 21-A and the Western Electric D 86844 both of which have
been described in some detail in this thesis. Like these, the TMV 75B
consists essentially of a superheterodyne receiver, a calibrating
oscillator and a loop antenna. The intermediate frequency of this
receiver is 300 kilocycles. The calibrating voltage is inserted at
the center of the loop by means of a mutual inductor attenuator the
secondary of which is connected in the loop circuit at all times
thus avoiding any changeing of loop constants. A thermocouple volt
meter which is free from any frequency characteristics is connected
across the primary of the inductor attenuator so that a constant
,voltage may be impressed at the center of the loop when calibrating
the equipment.

A stepped calibrated attenuator is placed at the input to
the intermediate frequency stages similiar to the Western Electric
equipment. by means of this attenuator the signal appearing at its
inwut may be att nuated by any amount up to BOOCO. If it is desired

5

to measure larger signal: a capacitance attenuator is snitcied into

1 "

tie “iTCuft aLaaC (i the first detector to avoid overloading this
tube. The second detector is designed to operate as a linear output
voltmeter.

This field intensity meter is distinguished by its ease of

operation,its rugged construction and its frequency range. It is

capable of measuring signals varying in field intensity from
20 microvolts to 5 volt: per meter at any frequency within the
the limits of 500 and 20000 kilocycles per second. When properly
Operated the meter has an accuracy of five percent over this range
of frequency and field intensity.

The meter used by Edwards and Martin is mounted on sponge
rubber in a ford station wagon with special wood panelled sides and
back to avoid shielding of the loop. Pictures of this car and the

field intensity meter are shown.

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