Date of Award

2018

Document Type

Open Access Thesis

Department

Electrical Engineering

Sub-Department

College of Engineering and Computing

First Advisor

Mohammod Ali

Abstract

As the number of installed antennas increases on a structure, the available real estate to do so without each antenna interfering with the others diminishes. Electromagnetic band gap (EBG) structures are one way to mitigate this cosite interference with compact antenna installations. While a host of EBG structures and types (3-D, planar etc.) have been proposed and studied historically, it has been found that planar EBG structures tend to provide very narrow bandwidths for both antenna design and cosite interference reduction. This research focuses on the design of EBG structures intended to achieve greater than 20 dB of isolation improvement in the 960-1220 MHz frequency band. Since the antenna bandwidth to be supported is quite substantial, our focus was to investigate the 3-D mushroom EBG structure or the so called Sievenpiper EBG structure [1].

In this research, many models and simulations including parametric optimization were performed to meet the isolation improvement goal across the desired frequency while maintaining return loss performance, radiation pattern, and gain. Focus was also placed in terms of the practicality of fabricating the EBG structure in terms of materials, size, and weight. And thus subsequently more practical approaches to traditional mushroom EBGs were developed that include EBG patches printed on very thin sheets of dielectric materials and are supported by thick foam substrates. Ultimately, the simulated results of an EBG design capable of improving isolation between blade antennas by at least 20 dB from 980-1240 MHz is presented. Efforts in developing an analytical model of such a structure based on lumped circuit elements is also discussed.

Available for download on Sunday, May 12, 2019

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