الفهرس 
INTRODUCTION TO ULTRA- WIDEBAND ANTENNASOnly 14 pages are availabe for public view
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Abstract
Ultra-wideband (UWB) systems are recent systems that have significantly wider
bandwidths than conventional systems. They” have the potential for high data rate
transmission which is very desirable in communication systems. They can also give high
resolution in radar and localization applications. Several factors affect the operation ofUWB
such as the channel characteristics, difficulties associated with UWB signal processing and
the transmission and reception ofUWB signals through UWB antennas.
A large number of UWB antennas were introduced in the literature such as TEM horns,
UWB dipoles and monopoles and Vivaldi antennas. However, few attempts have been made
to categorize these antennas and obtain physical insight into their operation. In this research,
a comprehensive survey on some types of UWB antennas has been performed. Their
principles of operation and reasons for their UWB operation are investigated. A method of
moments, finite difference time domain and finite elements method codes were used to
model these antennas and predict their performance. Two global optimization techniques
were also employed to optimize these antennas.
This thesis is organized as follows:
in Chapter I, the basic antenna terms that are used throughout the thesis are introduced.
The definition of UWB antennas is presented together with the main differences in their
analysis as compared to the conventional narrowband antennas. Then, two UWB
applications, the ground penetrating radar and localization, are presented together with a
brief discussion of their antenna requirements. .
In Chapter 2, a survey on numerical techniques that can be used for modeling UWB
antennas is presented. The methods are categorized into frequency domain techniques and
time domain techniques. The frequency domain techniques include the method of moments,
the finite elements method and the finite difference frequency domain. The time domain
techniques include the method of moments in the time domain, the finite elements method in
time domain and the finite difference time domain.
In Chapter 3, a brief survey on the numerical techniques that can be used for optimizing
UWB antennas are presented. The methods are classified into local optimization techniques
and global optimization techniques. Quasi-Newton method as an example of local
optimization techniques is introduced. Genetic Algorithms and Artificial Neural Networks as
examples of global optimization techniques are presented.
In Chapter 4, the first type of UWB antennas, which is the UWB TEM hom antennas,
are presented. A conventional TEM hom is analyzed and its basic performance aspects were
investigated. A comprehensive literature survey on UWB TEM horns is then presented. An
extended band UWB spiral horn antenna is then analyzed and its principle of operation was
investigated. The antenna was modeled using a developed method of moments code and the
results are compared with the simulation results using a commercial finite difference time
domain simulator.
In Chapter 5, the second type of UWB antennas is introduced which are the UWB
dipoles and monopoles. A literature survey on UWB dipoles and monopoles is first