Electrical and Computer Engineering ETDs

Publication Date

2-9-2010

Abstract

The ability of reconfigurable antennas to tune resonances, change polarization and modify their radiation patterns, made their development imperative in modern telecommunication systems. Their agility and diversity created new horizons for different types of applications especially in cognitive radio, Multiple Input Multiple Output Systems, satellites and many other applications. Reconfigurable antennas satisfy the requirements for increased functionality, such as direction finding, beam steering, radar, control and command, within a confined volume. Since their rise in the last decade, reconfigurable antennas have made use of many reconfiguration techniques. The most common techniques utilized revolved around switching mechanisms. By combining low-loss, high-isolation switches such as MEMS or PIN diode switches with compatible antenna elements, we can physically reconfigure antennas and their feed structures providing frequency and polarization diversity. Other techniques such as the incorporation of variable capacitors, varactors and physical structure alteration surfaced recently to overcome many problems faced in using switches and their biasing. The aim of this work is to develop not only new reconfigurable antenna designs but to also establish guidelines for the design and optimization of these types of antennas. In this work a new approach for reducing redundancies in reconfigurable antennas structures using graph models as optimization tools is presented. The characteristics of various reconfigurable antennas are grouped, categorized and graph modeled according to a set of proposed rules. The optimized configurations of these antennas are presented and discussed to verify the validity of the new proposed approach. In addition to the use of graph models for the optimization approach their algorithms can be used to program field programmable gate arrays (FPGAs) to control reconfigurable antennas and automate their process. Moreover, in this work the level of uncertainties in a reconfigurable antenna structure, the reliability and correlation between the reliability and complexity of reconfigurable antennas are mathematically formulated. Information theory is used to predict the probability of error in a reconfigurable antenna system. This work also presents the different methods that can be utilized to adjust to failures of an antenna part and to ensure a smooth functioning of the defected reconfigurable antenna.

Keywords

Adaptive antennas., Adaptive antennas--Mathematical models., Field programmable gate arrays.

Document Type

Dissertation

Language

English

Degree Name

Electrical Engineering

Level of Degree

Doctoral

Department Name

Electrical and Computer Engineering

First Advisor

Christodoulou, Christos

First Committee Member (Chair)

Abdallah, Chaouki

Second Committee Member

Gilmore, Mark

Third Committee Member

Anagnostou, Dimitris

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