Corrugated horns for microwave antennas

243 Pages·1984·10.43 MB·English

by  Olver

ELECTROMAGNETIC WAVES SERIES 18
Corrugated horns
for microwave
antennas
P. J. B. Clarricoats and A. D. Olver
Peter Peregrinus Ltd.
on behalf of the Institution of Electrical Engineers
IEE Electromagnetic Waves Series 18
Series Editors: Professor P.J.B. Clarricoats
E.D.R. Shearman and J.R. Wait
Corrugated horns
for microwave
antennas
Previous volumes in this series
Volume 1 Geometrical theory of diffraction for
electromagnetic waves
Graeme L. James
Volume 2 Electromagnetic waves and curved
structures
Leonard Lewin, David C. Chang and
Edward F. Kuester
Volume 3 Microwave homodyne systems
Ray J. King
Volume 4 Radio direction-finding
PJ.D. Gething
Volume 5 ELF communications antennas
Michael L. Burrows
Volume 6 Waveguide tapers, transitions
and couplers
F. Sporleder and H.G. Unger
Volume 7 Reflector antenna analysis
and design
PJ. Wood
Volume 8 Effects of the troposphere on radio
communications
Martin P.M. Hall
Volume 9 Schuman resonances in the
earth-ionosphere cavity
P.V. Bliokh, A.P. Nikolaenko and
Y.F. Filippov
Volume 10 Aperture antennas and diffraction
theory
E.V. Jull
Volume 11 Adaptive array principles
J.E. Hudson
Volume 12 Microstrip antenna theory and design
J.R. James, P.S. Hall and C. Wood
Volume 13 Energy in Electromagnetism
H.G. Booker
Volume 14 Leaky feeders and subsurface radio
communications
P. Delogne
Volume 15 The Handbook of Antenna Design
Volume 1
Editors; A.W. Rudge, K. Milne,
A.D. Olver, P. Knight
Volume 16 The Handbook of Antenna Design
Volume 2
Editors: A.W. Rudge, K. Milne,
A.D. Olver, P. Knight
Volume 17 Surveillance Radar Performance
Prediction
P. Rohan
Corrugated horns
for microwave
antennas
RJ. B. Clarricoats and A. D. Olver
Peter Peregrinus Ltd
On behalf of The Institution of Electrical Engineers
Published by: Peter Peregrinus Ltd., London, UK.
© 1984: Peter Peregrinus Ltd.
All rights reserved. No part of this publication may be reproduced,
stored in a retrieval system or transmitted in any form or by any
means — electronic, mechanical, photocopying, recording or otherwise
without the prior written permission of the publisher.
While the author and the publishers believe that the information and
guidance given in this work is correct, all parties must rely upon their own
skill and judgment when making use of it. Neither the author nor the
publishers assume any liability to anyone for any loss or damage caused
by any error or omission in the work, whether such error or omission is
the result of negligence or any other cause. Any and all such liability is
disclaimed.
Clarricoats, P. J. B.
Corrugated horns for microwave antennas.
—(IEE electromagnetic waves series; 18)
1. Microwave antennas 2. Antennas, Reflector
3. Antenna feeds
I. Title li.Olver, A. D. III. Series
621.381'33 TK7871.6
ISBN 0 86341 003 0
Printed in England by Short Run Press Ltd., Exeter
Contents
Preface viii
Acknowledgments ix
1 Introduction 1
1.1 Historical observations 1
1.2 Organisation of the book 3
2 Introduction to hybrid-mode feeds 5
2.1 Illumination of a reflector antenna 5
2.2 Focal field of a reflector 10
3 Propagation and radiation characteristics of cylindrical corrugated
waveguides 20
3.1 Introduction 20
3.2 Propagation in cylindrical corrugated waveguide 22
3.3 Fields in cylindrical corrugated waveguide 35
3.4 Attenuation in corrugated waveguide 40
3.5 Radiation from corrugated waveguides 43
3.5.1 Introduction 43
3.5.2 Radiation from a circular aperture 45
3.6 Junctions in corrugated waveguides 50
3.7 Multimode corrugated waveguides 54
4 Propagation and radiation characteristics of conical corrugated wave-
guides 58
4.1 Introduction 58
4.2 Modal characteristics of corrugated conical horns 58
4.3 Radiation from corrugated conical horns by the spherical wave
expansion method 65
4.3.1 The spherical wave expansion method 65
4.3.2 Frequency dependence of crosspolar radiation field 68
vi Contents
4.4 Generation of higher order modes 69
4.4.1 Scattering at an abrupt discontinuity 71
4.4.2 Higher order mode generation at the throat 73
4.4.3 Mode conversion along a horn with constant flare angle 73
4.4.4 Mode conversion along a horn with variable flare angle 78
4.5 Radiation from corrugated horns by the Kirchhoff—Huygen
method 86
4.6 Comparison of predicted and measured radiation patterns 90
4.7 Radiation from corrugated horns by cylindrical waveguide
approximation 90
4.8 Radiation from conical corrugated horns by means of the
Laguerre— Gaussian expansion method 95
5 Design of cylindrical and conical corrugated horns 97
5.1 Introduction 97
5.2 Copolar radiation characteristics 100
5.3 Crosspolar radiation characteristics 114
5.4 Flare section of horn 122
5.5 Throat region of horn 128
5.6 Gain and directivity 135
5.7 Efficiency when used as a feed for a reflector 137
5.8 Horn design 141
5.8.1 Large aperture, narrow flare angle horns 141
5.8.2 Small aperture horns 143
5.8.3 Wide flare angle horns 145
5.8.4 Multimode horns 150
5.8.5 Broadband horns 153
5.8.6 Multifrequency horns 154
5.8.7 Compact horns 155
5.9 Numerical prediction of performance 156
5.9.1 Propagation characteristics 157
5.9.2 Radiation characteristics 160
6 Manufacture and testing of corrugated horns 163
6.1 Manufacture of corrugated horns 163
6.2 Testing of corrugated horns 169
6.2.1 Introduction 169
6.2.2 Types of test range 171
6.2.3 Anechoic chamber design for low crosspolarisation
horn measurement 172
6.2.4 Assessment of test range performance 175
6.2.5 Measurement of copolar and crosspolar patterns 177
6.2.6 Measurement of phase patterns and gain 180
Contents vii
7 Rectangular and elliptical corrugated horns 181
7.1 Introduction 181
7.2 Rectangular corrugated horns 181
7.2.1 Background 181
7.2.2 Two-walled rectangular corrugated waveguide 183
7.2.3 Four-wall rectangular corrugated waveguide 188
7.2.4 Radiation characteristics of rectangular corrugated
horns 190
7.3 Elliptical corrugated horns 193
Appendix 199
Bibliography 213
Programs 222
Index 227
Preface
The idea for a text on the theory and design of corrugated horns became apparent
to us during the late 1970s, as this type of feed became more and more widely
used in antennas. Generally, the corrugated horn offers the reflector antenna
designer the potential for producing antennas with higher efficiency, lower cross-
polarisation and lower sidelobes, and it can be fairly said to lie at the heart of most
optimally designed reflector antennas.
The book contains material which should be of value both to the designer and
the research worker. Parts have been presented previously by us, at various vacation
schools and in invited papers at conferences, over the last ten years, but the text
also contains many new results. Some of these are drawn from the theses of our
research students and from the work of others in our Electromagnetics Applications
Group at Queen Mary College in the University of London. To these people we
offer our warmest thanks; they are separately identified in the acknowledgments
which follows. A description of the organisation of the book is to be found in
Chapter 1, alongside a brief history of the subject.
Acknowledgments
The authors are indebted to many who have helped in the production of this text.
They would especially like to thank the following members of the Queen Mary
College Electromagnetics Applications Group, whose theoretical and experimental
contributions over the period 1968-83, have proved so valuable: Drs. Al-Hariri,
Chan, Chong, Elliott, Hockham, Mahmoud, Parini, Poulton, Saha, Salema and
Seng. They also thank Mr. Kolb who undertook many measurements in our Antenna
Laboratory; Messrs Ede, Fairbrass and Goose, whose excellent craftsmanship
produced many intricate feeds, and Miss Sandra O'Callaghan, who typed the
manuscript with great care and attention to detail. One of us (PJBC) is grateful
for the encouragement of his wife Phyl during the preparation of the text.