Microwave horns and feeds

503 Pages·1994·19.479 MB·English

by  A. D. Olver, P.J.B. Clarricoats, A.A. Kishk, L. Shafai

eLectromagnetic waves series 39
microwave
horns

and

feeds
a d olver, P J B clarricoats
a a Kishk and L shafai
IEE ELECTROMAGNETIC WAVES SERIES 39
Series Editors: Professor P. J. B. Clarricoats
Professor Y. Rahmat-Samii
Professor J. R. Wait
MICROWAVE
HORNS
and
FEEDS
Other volumes in the IEE Electromagnetic Waves Series:
Volume 1 Geometrical theory of diffraction for electromagnetic waves
G. L. James
Volume 2 Electromagnetic waves and curved structures L. Lewin,
D. C. Chang and E. F. Kuester
Volume 3 Microwave homodyne systems R. J. King
Volume 4 Radio direction-finding P. J. D. Gething
Volume 5 ELF communications antennas M. L. Burrows
Volume 6 Waveguide tapers, transitions and couplers F. Sporleder and
H. G. Unger
Volume 7 Reflector antenna analysis and design P. J. Wood
Volume 8 Effects of the troposphere on radio communications
M. P. M. Hall
Volume 9 Schumann resonances in the earth-ionosphere cavity
P. V. Bliokh, A. P. Nikolaenko and Y. F. Flippov
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 A. W. Rudge,
K. Milne, A. D. Olver, P. Knight (Editors)
Volume 16 The handbook of antenna design, Volume 2 A. W. Rudge,
K. Milne, A. D. Olver, P. Knight (Editors)
Volume 17 Surveillance radar performance prediction P. Rohan
Volume 18 Corrugated homs for microwave antennas P. J. B. Clarricoats
and A. D. Olver
Volume 19 Microwave antenna theory and design S. Silver (Editor)
Volume 20 Advances in radar techniques J. Clarke (Editor)
Volume 21 Waveguide handbook N Marcuvitz
Volume 22 Target adaptive matched illumination radar D. T. Gjessing
Volume 23 Ferrites at microwave frequencies A. J. Baden Fuller
Volume 24 Propagation of short radio waves D. E. Kerr (Editor)
Volume 25 Principles of microwave circuits C. G. Montgomery,
R. H. Dicke, E. M. Purcell (Editors)
Volume 26 Spherical near-field antenna measurements J. E. Hansen
(Editor)
Volume 27 Electromagnetic radiation from cylindrical structures
J. R. Wait
Volume 28 Handbook of microstrip antennas J. R. James and P. S. Hall
(Editors)
Volume 29 Satellite-to-ground radiowave propagation J. E. Allnutt
Volume 30 Radiowave propagation M. P. M. Hall and L. W. Barclay
(Editors)
Volume 31 Ionospheric radio K. Davies
Volume 32 Electromagnetic waveguides: theory and application S. F. Mahmoud
Volume 33 Radio direction finding and superresolution P. J. D. Gething
Volume 34 Electrodynamic theory of superconductors S.-A. Zhou
Volume 35 VHF and UHF antennas R. A. Burberry
Volume 36 Propagation, scattering and dissipation of electromagnetic waves
A. S. llyinski, G. Ya. Slepyan and A. Ya. Slepyan
Volume 37 Geometrical theory of diffraction V. A. Borovikov and B. Ye. Kinber
Volume 38 Analysis of metallic antennas and scatterers B. D. Popovi6 and
B. M. Kolundiiya
MICROWAVE
HORNS
and
FEEDS
A D Olver, P J B Clarricoats
A A Kishk and L Shafai
IEE
The Institution of Electrical Engineers
IEEE
PRESS
The Institute of Electrical and Electronics Engineers, Inc., New York
Copublished by: The Institution of Electrical Engineers,
London, United Kingdom, and the Institute of Electrical
and Electronics Engineers, Inc., New York, USA
© 1994: The Institution of Electrical Engineers
Distribution in North and South America is by the IEEE Press
ISBN 0 70)31115 9
IEEE Order No. PC4689
Distribution elsewhere is by the IEE
ISBN 085296 809 4
This publication is copyright under the Berne Convention and the
Universal Copyright Convention. All rights reserved. Apart from any fair
dealing for the purposes of research or private study, or criticism or
review, as permitted under the Copyright, Designs and Patents Act, 1988,
this publication may be reproduced, stored or transmitted, in any forms or
by any means, only with the prior permission in writing of the publishers,
or in the case of reprographic reproduction in accordance with the terms
of licences issued by the Copyright Licensing Agency. Inquiries
concerning reproduction outside those terms should be sent to the
publishers at the undermentioned address:
The Institution of Electrical Engineers,
Michael Faraday House,
Six Hills Way, Stevenage,
Herts. SG1 2AY, United Kingdom
While the authors 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 authors 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.
The moral right of the authors to be identified as authors of this work has
been asserted by them in accordance with the Copyright, Designs and
Patents Act 1988.
British Library Cataloguing in Publication Data
A CIP catalogue record for this book
is available from the British Library
ISBN 0 85296 809 4
Printed in England by Bookcraft, Bath
Contents
Preface x
1 Introduction 1
A.D. Olver and PJ.B. Clarrieoats
1.1 Preliminary remarks 1
1.2 History of reflector antennas and feeds 1
1.3 Performance requirements of feeds and reflectors 5
1.3.1 Spatial characteristics 5
1.3.2 Impedance characteristics 9
1.3.3 Frequency characteristics 10
1.4 Organisation of the book 10
1.5 Choice of type of feed 14
1.6 References 15
2 Reflector antennas 16
PJ.B. Clarrieoats
2.1 Introduction 16
2.1.1 General remarks 16
2.1.2 Reflector types 16
2.1.3 Constraints 17
2.2 Theory and performance of reflector antennas 18
2.2.1 The scattered field from a reflector 18
2.2.2 The aperture-field method 22
2.2.3 Radiation from a symmetrical paraboloidal reflector 22
2.2.4 Features of the secondary-radiation pattern 24
2.2.5 The dual-reflector antenna 29
2.2.6 The offset-reflector antenna 32
2.2.7 The dual-offset-reflector antenna 40
2.2.8 Focal-field analysis 46
2.2.9 Antenna return loss 51
2.2.10 Radome-covered reflectors 53
2.2.11 The effect of reflector surface errors on antenna performance 57
2.2.12 The effect of positional errors on antenna performance 60
2.2.13 Analysis and synthesis of shaped-beam antennas 61
2.2.14 Dual-gridded reflector antennas 71
2.2.15 Reconfigurable reflector antennas 72
2.2.16 Dichroic reflectors 74
2.3 References 77
3 Radiation from apertures 79
A.D. Olver
3.1 Introduction 79
3.2 Radiation equations from aperture fields 80
vi Contents
3.3 Radiation characteristics from apertures 84
3.3.1 Solution of radiation equations 84
3.3.2 Line-source apertures 85
3.3.3 Compound aperture distributions 87
3.3.4 Rectangular apertures 89
3.3.5 Apertures with phase tapers 90
3.3.6 Circular apertures 92
3.3.7 Gaussian aperture distributions 95
3.4 Directivity of apertures 96
3.5 Near fields 97
3.6 References 98
4 Numerical analysis using cylindrical and spherical waves in horns 100
A.D. Olver
4.1 Introduction 100
4.2 Fundamentals of modal analysis 101
4.3 Cylindrical-wave analysis 102
4.4 Spherical-wave analysis 105
4.5 Principles of modal-matching technique 106
4.5.1 Scattering matrix of a uniform section 110
4.5.2 Scattering matrix of a junction 110
4.6 Modal-matching technique for cylindrical waveguides 113
4.6.1 Numerical procedure 114
4.6.2 Number of modes and sections 115
4.7 Spherical-modal-matching technique for conical waveguides 117
4.8 References 122
5 Numerical analysis of small axisymmetric feeds 123
A.A. Kishk and L. Shafai
5.1 Introduction 123
5.2 Basic formulation 125
5.3 Moment-method solution 129
5.3.1 Co-ordinates of bodies of revolution 129
5.3.2 Application of moment method 131
5.3.3 Excitation vectors 136
5.3.4 Computation of the radiation patterns 139
5.3.5 Different integral-equation formulations 143
5.3.6 Solution verification 145
5.4 References 148
6 Pure-mode horns 149
A.D. Olver
6.1 Principles of pure-mode horns 149
6.2 Fields and modes in cylindrical waveguides 150
6.3 Conical horns 152
6.3.1 Radiation patterns 154
6.3.2 Gain 157
6.3.3 Optimum designs 157
6.3.4 Phase centre 159
6.4 Pyramidal horns 160
6.4.1 Radiation patterns 162
6.4.2 Gain 165
6.4.3 Design of pyramidal horns 167
6.5 Other shaped-aperture horns 168
Contents vii
6.6 Wideband ridge-loaded horns 172
6.6.1 Radiation patterns 174
6.6.2 Ridge-loaded input section 174
6.7 References 178
Prime-focus waveguide feeds 181
L. Shafai and A.A. Kishk
7.1 Introduction 181
7.2 Phase-centre determination 182
7.3 Circular waveguide feeds 185
7.4 Circular waveguide with rectangular corrugated flange 200
7.5 Circular waveguide with trapezoidally corrugated flange 203
7.6 Phase-error effects 208
7.7 Coaxial waveguide feeds 209
7.8 Feeds for deep reflectors 218
7.9 Dualband feeds 222
7.10 Small-horn feeds 225
7.11 References 227
Multimode horns 229
A.D. Olver
8.1 Introduction 229
8.2 Multiple modes in cylindrical waveguides 230
8.2.1 Circular waveguides 232
8.2.2 Rectangular waveguides 241
8.2.3 Other waveguide cross-sections 241
8.3 Excitation of higher-order modes 244
8.4 Shaped-pattern horns 246
8.4.1 Horns for pattern symmetry and low crosspolarisation 246
8.4.2 Horns for increased aperture efficiency 249
8.4.3 Matched feed horns for offset reflectors 253
8.5 Tracking horns 253
8.6 References 255
Corrugated horns 258
A.D. Olver
9.1 Introduction 258
9.2 Principles of operation of corrugated horns 259
9.3 Design procedure for corrugated horns 261
9.4 Analytical techniques for predicting performance 265
9.4.1 Balanced hybrid model 266
9.4.2 Impedance techniques: cylindrical 266
9.4.3 Impedance techniques: spherical 271
9.4.4 Space-harmonic techniques 274
9.4.5 Modal-matching techniques: cylindrical 275
9.4.6 Modal-matching techniques: spherical 278
9.4.7 Gaussian-beam techniques 282
9.5 Types of corrugated horn 286
9.5.1 Standard narrow-flare-angle horns 286
9.5.2 Small-aperture horns 287
9.5.3 Millimetre-wave horns 287
9.5.4 Wide-flare-angle horns 288
9.5.5 Broadband corrugated horns 296
9.5.6 Ring-loaded slots 298
viii Contents
9.5.7 Dual-depth corrugated horns 300
9.5.8 Profile corrugated horns 305
9.5.9 Rectangular corrugated horns 313
9.6 References 315
10 Dielectric-loaded horns 318
A.D. Olver
10.1 Introduction 318
10.2 Principle of operation 321
10.3 Prediction using modal-matching technique 322
10.3.1 Dielectric-filled circular waveguide 323
10.3.2 Power-coupling integrals 328
10.4 Design considerations 328
10.5 Parametric studies on linear horn 330
10.5.1 Permittivity of dielectric 330
10.5.2 Variation of aperture diameter 331
10.5.3 Airgap 332
10.5.4 Change in flare angle 332
10.5.5 Design of throat region 332
10.6 Horn-design examples 336
10.6.1 Dielectric-foam cone in metal horn 337
10.6.2 Metallised dual-dielectric cone-loaded horn 338
10.6.3 Millimetre-wave horns using a solid-dielectric cone 342
10.6.4 Millimetre-wave horns using two solid dielectrics 342
10.7 Compact profiled dielectric-loaded horns 346
10.7.1 Comparison with linear horn 347
10.7.2 Reduction in length 350
10.7.3 Influence of shape of profile 352
10.8 Dielectric losses in a dielectric-loaded conical horn 356
10.8.1 Perturbation expression for the attenuation coefficient 357
10.8.2 Losses in dielectric-loaded horn 358
10.9 Tolerance on relative permittivity of dielectric 361
10.10 Control of crosspolarisation and efficiency with a lens 364
10.10.1 Lens profile 364
10.10.2 Design of lens to improve efficiency 365
10.10.3 Design of lens to reduce crosspolarisation 366
10.11 References 368
11 Lens-corrected horns 370
A.D. Olver
11.1 Introduction 370
11.2 Theory of lens design 371
11.3 Plastics-foam lenses 373
11.4 Shape of lens 373
11.5 Zoned lenses 378
11.6 Aperture amplitude distribution 379
11.7 Radiation characteristics 383
11.8 Experimental lenses 387
11.9 Uses of lens-corrected horns 389
11.10 References 390
12 Dielectric feeds 391
L. Shafai and A.A. Kishk
12.1 Introduction 391
Contents ix
12.2 Dielectric-rod feed 392
12.2.1 Dielectric-diameter effect 397
12.2.2 Dielectric constant 397
12.3 Dielectric-rod feed with ring loading 401
12.4 Dielectric rod with cavity loading 404
12.5 Profiled dielectric rods 407
12.6 Waveguides with dielectric rings 409
12.7 Dualband feed 411
12.8 References 414
13 DDiippoollee ffeeeeddss 416
L. Shafai and A.A. Kishk
13.1 Introduction 416
13.2 Ring-loaded dipole-disc feed 417
13.3 Cone-dipole feed 419
13.4 Cavity-dipole feed 423
13.5 References 426
14 Microstrip and resonator type feeds 427
L. Shafai and A.A. Kishk
14.1 Introduction 427
14.2 Microstrip-antenna feed 428
14.3 Effect of mode excitation on the crosspolarisation 431
14.4 Effect of conducting chokes 432
14.5 Feed performance with the reflector antenna 434
14.6 Patch-ring feed 436
14.7 Dielectric-resonator feed 438
14.8 References 443
15 Array feeds 444
PJ.B. Clarricoats
15.1 Introduction 444
15.2 Mutual coupling in an array 448
15.2.1 Fundamentals 448
15.2.2 Mutual coupling in an array of conical horns 448
15.2.3 Mutual-coupling predictions for conical-horn arrays 452
15.3 Effect of mutual coupling on secondary patterns 461
15.3.1 Prediction methods 461
15.3.2 Predicted primary and secondary patterns 464
15.3.3 Effect of mutual coupling on secondary patterns when the
array feed is displaced 469
15.4 Mutual coupling for elements of rectangular and elliptical
cross-sections 472
15.5 Mutual coupling for a microstrip patch array 475
15.6 References 480
15.7 Appendix: Coefficients of the admittance matrix for an array of
circular apertures 480
Index 483