Metamaterials are artificially engineered macroscopic composites that are designed to produce a combination of permittivity and permeability properties that are not readily available in nature. The creation of metamaterial media relies on embedding metallic or dielectric inclusions into a host medium, with the most common metallic inclusions being split ring resonators and their derivatives. Unfortunately, these resonant structures have limited flexibility since their design involves very few parameters such as ring radii and slot widths, which do not allow for much tuning of the material properties. Additionally, the performance of these resonant structures is dependent on the orientation of the exciting electric and magnetic fields. When placed next to a device, the effects of mutual coupling usually lead to an undesirable performance of the combined structure, which is coined a ``metamaterial-inspired device". Therefore, additional tuning of the resonant structure becomes necessary to achieve the desired performance of the metamaterial-inspired device.This dissertation introduces a new design methodology that can be used to synthesize new resonant structures for the design of metamaterial media. By using a pixelization approach with a binary optimizer such as a genetic algorithm, it is shown that it is possible to create resonant structures quite different from SRRs and with improved flexibility. This dissertation also introduces an in situ optimization technique as an effective means to naturally compensate for the mutual coupling between the metamaterial elements and the surrounding structure. Using a combination of the pixelization approach and the in situ optimization technique, it is shown that it is possible to create metamaterial-inspired RF components that outperform existing RF components. Designs and prototypes of various metamaterial-inspired miniaturized patch antennas, loop antennas, folded monopole antennas, ultra-compact broadband waveguide filters, and widely tunable resonant structures that are easy to fabricate and at a low cost are presented.
Read
