Date of Award

1-30-2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Systems Engineering

First Advisor

Hussain Al-Rizzo

Abstract

This dissertation focuses on the use of nano-scale and metamaterial structures for modern antenna applications including wearable devices, Global Positioning Systems, and self-powered wearable systems. Conductive composites, thin films, and array crystallography are nanostructural materials with superior properties that can be applied to printed electronic circuits, antennas, and optoelectronic devices. The feasibility of using conductive multi-walled carbon nanotube composites for printing patch antennas operating in the microwave range is demonstrated for the first time. A flexible meander sinusoidal patch based on a thin film of copper is presented for wearable medical telemetry devices. The effects of twisting and bending on the performance of the meander patch are investigated in close proximity to the human body. The scattering, absorption, and reflection characteristics of 2-D arrays of finite-length, armchair, single-walled carbon nanotubes are reported in the visible frequency regime for solar cell applications based on three geometrical models: solid cylinder, hollow cylinder, and honeycomb. The electromagnetic characteristics of nano shell-silver coated silica array for solar cell applications are evaluated based on three electromagnetic approaches: frequency selective surfaces, metamaterials, and electromagnetic band gaps. The metamaterial approach examines the use of electromagnetic band gaps and negative refractive index structures in two antenna applications. In the first application, the use of uniplanar compact-photonic band lenses to improve the directivity of planar microstrip antennas is explored. An algorithm based on Fourier optics combined with an array signal processing approach is developed to explain the gain enhancement achieved by placing uniplanar compact-photonic band gap lenses on top of microstrip antennas. The proper position of these lenses and their separation are identified using ray tracing and classical optics. The second application involves the use of anisotropic Metamaterial structures based on Hilbert-shaped unit metamaterial and square electromagnetic band gap defects on the ground plane for directing antenna radiation to the end fire.

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