Radiation characteristics of corner reflector antennas.

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Radiation characteristics of corner reflector antennas.
Sterr, U.

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RADIATION CHARACTERISTICS OF
CORNER REFLECTOR ANTENNAS
A Thesis for
the
presented
degree Doctor Philosophy
of of
in Faculty Engineering
the of of
University London
the
of
by
U. Sterr
Engineering
Electronic
Department
of
Westfield College
Queen Mary
and
University London
of
January, 1998
ACKNOWLEDGMENTS
The
like his
author would to express most sincere thanks to:
Professor A. D. Olver for his
o throughout the
supervision and continued guidance
project.
The Queen Mary & Westfield College for financial
the
9 support which enabled me
to the
undertake research.
Professor P. J. B. Clarricoats for his interest his
* active and advice.
Professor H. Khakzar horizon beyond boarders Germany.
the
* who opened my of
Dr. M. Rayner for his help hours fruitful discussions.
* and of
Mr. J. Dupuy Mr. M. Johnson for their help the
9 and expert and assistance with
experimental programme.
* The other members of the Microwave Research group for their help.
Ms A Hedderich for her
never ending patience and support.
*
My former Mr. MoBbeck, Mr. Hdrle, Dr. Freytag, Prof. Martin, Prof
teachers
*
Herter Prof Mer did than they to
who so much more were obliged and made
and
difference.
the
all
11
ABSTRACT
This
thesis
presents a study of the
radiation characteristics of corner reflector
The influence
design
antennas.
the
of the
parameters on radiation characteristics are
assessed using an analytical the Finite Difference Time Domain (FDTD)
method and
method.
The FDTD for
method corner reflector antennas which are electrically small to
is developed in detail. The important
medium sized antennas the Absorbing
subject of
Boundary Conditions
(ABCs) is including Mur ABC Perfectly
studied a study of and
Matched Layers. It is
both from
shown that methods reduce the reflections the
boundaries
far-field be
sufficient so that the
radiation pattern can computed
accurately.
An far-field for infinite
to the
analytical solution compute radiation pattern comer
is derived Based
to the
reflector antennas and used understand radiation mechanisms.
FDTD is finite
those the to
on results, method used conduct a paramtetric study on
Experimental have been built
sized comer reflector antennas. antennas and measured
in Very is
to the
order verify computational predictions. good agreement reported
The idea beam-width is developed
novel of a variable comer reflector antenna and
designs The is design
to the
practical of such an antenna are presented. principle
beam-width be
that the the
comer reflector antenna such of antenna can precisely
Data beam-width This has been done both by
the
modified. on gain and are presented.
by
computational and an experimental model.
The influence on the performance of the comer reflector antenna when substituting
by has been investigated. The
the solid reflector plates rods computational predictions
Very
by
have been
measurements of an experimental antenna. good
verified
has been
achieved.
agreement
III[
The
is investigated.
possibility of modifying the shape of the comer reflector antenna
It is
less depth
shown that the
a modified comer reflector antenna with produces same
far-field
It is
pattern as a standard corner reflector antenna. also shown that the
is
performance of small aperture size corner reflector antennas superior to a
cylindrical
parabolic reflector antenna.
IV
TABLE OF CONTENTS
CHAPTER1
INTRODUCTION 1
1.1.
Introduction
1
1.2. Plan
thesis 4
of
CHAPTER
2
THE CORNER REFLECTOR ANTENNA: HISTORY
AND ANALYSIS
6
2.1. Introduction
6
2.2. Definition 8
and application
2.3. Literature 10
survey
2.4. Analytical 16
prediction of radiation characteristics
2.4.1. Image Theory 16
2.4.2. Wait's Method 19
2.4.2.1. Some Bessel functions 23
properties of
2.4.2.2. Interpretation Wait's 23
of equation
Directivity directivity 27
2.4.3.
the
and peak
33
Summary
2.5.
V
CHAPTER3
FINITE DIFFERENCE TIME DOMAIN (FDTD)
TECHNIQUE FOR MODELLING CORNER
REFLECTOR ANTENNAS 34
3.1. Introduction 34
3.2. The Finite Difference Time Domain (FDTD) 35
method
3.2.1. The FDTD, Spatial Domain 37
38
3.2.2. Formulation FDTD, Algorithm
the
of
42
3.2.3. Excitation Functions
43
3.2.4. Numerical Stability
44
3.2.5. Numerical Dispersion
45
3.2.6. Geometry Specification
45
Conditions
3.3. Analysis Absorbing Boundary
of
46
3.3.1. Mur Absorbing Boundary Conditions
49
3.3.2. Berenger Perfectly Matched Layer (PML)
59
Comparison Mur PML ABCs
3.3.3.
and
60
Calculation
3.4. Far-Field Radiation Pattern
60
Conversion
Time Domain Frequency Domain
3.4.1. to
62
3.4.2. Field Equivalence
principle
65
Code
3-D FDTD Modelling
Specification
3.5.
of
65
Code Verification
FDTD
3.6.
66
Analytical
3.6.1.
verification
67
Measurement
3.6.2.
validation
67
Design
3.6.2.1.
of the comer reflector antennas
68
Measurement
3.6.2.2.
set up
vi
3.6.2.3. Results for 1
73
antenna
3.6.2.4.
Results for 2
75
antenna
3.6.3.
Summary
77
3.7.
Development
2-D FDTD
78
of a
code
3.7.1.
The FDTD domain
79
spatial
3.7.2.
The Absorbing Boundary Conditions
81
3.7.3.
Far-field
81
radiation pattern calculation
3.7.4.
Considerations
for
84
parametric studies.
3.7.5.
Validation Code
87
the
of
3.7.6. Summary
88
3.8. Other
techniques 89
3.8.1. Method Moments (MM) 89
of
3.8.2. Geometrical
Theory Diffraction (GTD) 91
of
3.9. Summary 92
CHAPTER4
SOLID CORNER REFLECTOR ANTENNA 94
4.1. Finite difference domain for
time
method applied corner
96
reflector antenna
97
4.1.1. Modelling
the
reflector
4.1.2. Comparison between 2-D FDTD Wait's 109
and method
4.1.3. Comparison between 2-D 3-D FDTD
and corner
113
reflector antenna simulations
4.1.4. Establishing influence ABCs 115
the the
of
4.2. The H-plane Directivity 118
Definition H-plane directivity 118
4.2.1.
of
4.2.2. Influence length H-plane directivity
the
of plate on
in infinite 119
case of wide plates
VIII
4.3.
Aperture Efficiency 126
4.3.1.
Definition 126
of aperture efficiency
4.3.2. Influence length in
of plate on aperture efficiency
infinite 127
case of wide plates
4.4. Ray
129
tracing
model
4.4.1. Basic 130
expressions
4.4.2. Results 134
tracing
of ray on comer reflector antenna
4.5. Influence finite in
three
of sized reflector plates
dimensions 140
4.6. Variable beam-width 143
corner reflector antenna
4.6.1. Measurement 147
results
4.6.2. Gain 149
measurements
4.6.3. Gain 149
transfer
measurement method
150
4.6.4. Gain
measurement set-up
151
4.6.5. Gain
measurement results
152
4.6.6. Discussion
the
of results
153
4.7. Feed
study
153
4.7.1. Feeds directivity
and
154
4.7.2. Feeds bandwidth
and
162
4.8. Summary
VRI
CHAPTER
5
GRIDDED
CORNER REFLECTOR
ANTENNA
165
5.1.
Introduction
165
5.2.
FDTD
166
modelling of rods
5.2.1.
Monostatic
RCS
167
of smaU sphere
5.2.2.
Bistatic RCS
169
of a rod
5.2.3.
Minimum distance between
171
rods
5.3. Experimental
the 172
verification of methods
5.3.1.
Design
the 172
of gridded comer reflector antenna
5.4. Comparison
dimensional
two
of gridded- solid- and solid
176
corner reflector antenna
5.5. Band-width
178
considerations
5.6. Influence
179
of rod spacing
5.7. Parametric H-plane directivity front-to-back
study of and
182
ratio
5.8. Summary 189
6
CHAPTER
SHAPING OF THE REFLECTOR PLATES 190
6.1. Modified 190
corner reflector antenna
6.1.1. Geometry 190
of modified comer reflector antenna
6.1.2. H-plane directivity front-to-back for
and ratio
191
modified comer reflector antenna
6.1.3. H-plane
radiation pattern of modified corner
197
reflector antenna
Ix