Compact Antennas for Wireless Communications and Terminals: Theory and Design

249 Pages·2011·19.09 MB·English

Compact Antennas for Wireless Communications and Terminals
To my sons Tanguy and Térence
Compact Antennas for Wireless
Communications and Terminals
Theory and Design

Edited by
Jean-Marc Laheurte
First published 2011 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc.
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 only be reproduced,
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The rights of Jean-Marc Laheurte to be identified as the author of this work have been asserted by him in
accordance with the Copyright, Designs and Patents Act 1988.
____________________________________________________________________________________
Library of Congress Cataloging-in-Publication Data

Compact antennas for wireless communications and terminals : theory and design / edited by Jean-Marc
Laheurte.
p. cm.
Includes bibliographical references and index.
ISBN 978-1-84821-307-4
1. Antennas (Electronics)--Design and construction. 2. Wireless communication systems. I. Laheurte,
Jean-Marc.
TK7871.6.C626 2011
621.384'135--dc23
2011021212

British Library Cataloguing-in-Publication Data
A CIP record for this book is available from the British Library
ISBN 978-1-84821-307-4

Printed and bound in Great Britain by CPI Antony Rowe, Chippenham and Eastbourne.
Table of Contents
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
Chapter 1. General Information About Printed Antennas. . . . . . . . . . . 1
Jean-Marc LAHEURTE
1.1. Physical characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2. Properties, limitations, and applications. . . . . . . . . . . . . . . . . . . 4
1.3. Printed rectangular antenna viewed as a wide microstrip line . . . . . . 7
1.4. Manufacturing processes. . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.5. Microwave substrates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Chapter 2. Transmission Line Model. . . . . . . . . . . . . . . . . . . . . . . . 15
Jean-Marc LAHEURTE
2.1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.2. Equivalent circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.2.1. Effective permittivity. . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.2.2. Equivalent line extension . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.2.3. End of line equivalent circuit. . . . . . . . . . . . . . . . . . . . . . . 17
2.2.4. Process for design of a rectangular antenna . . . . . . . . . . . . . . 19
2.2.5. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.3. Input impedance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Chapter 3. Cavity Model. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Jean-Marc LAHEURTE
3.1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.2. Formulation of the electromagnetic problem . . . . . . . . . . . . . . . . 25
3.3. Calculation of expressions for fields and currents of a
rectangular patch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
vi Compact Antennas for Wireless Communications & Terminals
3.4. Expressions for principal modes . . . . . . . . . . . . . . . . . . . . . . . 31
3.5. Cartography of modal currents and associated
radiation patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Chapter 4. Radiation of a Printed Antenna . . . . . . . . . . . . . . . . . . . . 39
Jean-Marc LAHEURTE
4.1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.2. Modelization using two equivalent radiating slots. . . . . . . . . . . . . 40
4.3. Calculation of the field radiated by a horizontal radiating slot. . . . . . 43
4.4. Calculation of the field radiated by the rectangular patch. . . . . . . . . 44
4.5. Determination of the radiation pattern in the principal planes . . . . . . 44
4.6. Influence of height. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
4.7. Influence of the ground plane . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.8. Polarization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
4.9. Directivity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
4.10. Influence of the substrate on resonant frequency: parametric
study based on antenna RCS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Chapter 5. Electrical Equivalent Circuit of a Printed Antenna. . . . . . . . 55
Jean-Marc LAHEURTE
5.1. Energy considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
5.2. Equivalent circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
5.3. Determination of W , W , and B for a rectangular patch. . . . . . . . . 58
E M
5.4. Modeling using a tank circuit . . . . . . . . . . . . . . . . . . . . . . . . . 60
5.5. Quality factor of an antenna . . . . . . . . . . . . . . . . . . . . . . . . . . 62
5.6. Calculation of radiation quality factor . . . . . . . . . . . . . . . . . . . . 63
5.7. Calculation of efficiency. . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
5.7.1. Losses in conductive walls . . . . . . . . . . . . . . . . . . . . . . . . 64
5.7.2. Losses in the dielectric. . . . . . . . . . . . . . . . . . . . . . . . . . . 65
5.7.3. Radiated power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
5.8. Influence of surface waves on bandwidth and efficiency. . . . . . . . . 67
Chapter 6. Feeding Circuits for Microstrip Antennas . . . . . . . . . . . . . 69
Jean-Marc LAHEURTE and Benoît POUSSOT
6.1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
6.2. Direct coupling by coaxial probe . . . . . . . . . . . . . . . . . . . . . . . 71
6.3. Excitation by proximity coupling. . . . . . . . . . . . . . . . . . . . . . . 73
6.4. Excitation by slot coupling. . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Table of Contents vii
Chapter 7. Circularly Polarized Antennas. . . . . . . . . . . . . . . . . . . . . 89
Jean-Marc LAHEURTE, Marjorie GRZESKOWIAK and Stéphane PROTAT
7.1. Principles of circular polarization. . . . . . . . . . . . . . . . . . . . . . . 90
7.1.1. Elliptical and circular linear polarization. . . . . . . . . . . . . . . . 90
7.1.2. Right- or left-hand circular polarization. . . . . . . . . . . . . . . . . 91
7.1.3. Axial and cross-polarization ratios. . . . . . . . . . . . . . . . . . . . 92
7.1.4. Measurement of circular polarization . . . . . . . . . . . . . . . . . . 93
7.2. Parasitic radiation – degradation of circular polarization. . . . . . . . . 94
7.3. Patch fed by single or dual excitation . . . . . . . . . . . . . . . . . . . . 96
7.3.1. Single excitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
7.3.2. Dual excitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
7.4. Sequential array . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
7.4.1. Principle of sequential rotation: initial analysis . . . . . . . . . . . . 99
7.4.2. Sequential rotation applied to a radiating element fed by
multiple feeds. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
7.5. Spiral and quadrifilar helix antennas. . . . . . . . . . . . . . . . . . . . . 108
7.5.1. Spiral antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
7.5.2. Quadrifilar helix antennas. . . . . . . . . . . . . . . . . . . . . . . . . 113
7.6. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Chapter 8. Wideband Antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Xavier BEGAUD
8.1. Multiresonant antennas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
8.1.1. Principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
8.1.2. Widening bandwidth through resonance coupling . . . . . . . . . . 122
8.2. Traveling wave antennas. . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
8.2.1. Tapered slot antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
8.3. Frequency independent antennas . . . . . . . . . . . . . . . . . . . . . . . 126
8.3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
8.3.2. Equiangular antennas. . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
8.3.3. Log-periodic antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
8.3.4. Sinuous antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
8.4. Ultra-wideband antennas. . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
8.4.1. Biconical and Bow-Tie antennas. . . . . . . . . . . . . . . . . . . . . 134
8.4.2. Planar monopoles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
8.5. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Chapter 9. Miniature Antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Guillaume VILLEMAUD
9.1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
9.2. Which types of antennas should be used for integration?. . . . . . . . . 144
9.2.1. Non-resonant antennas. . . . . . . . . . . . . . . . . . . . . . . . . . . 144
viii Compact Antennas for Wireless Communications & Terminals
9.2.2. Resonant antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
9.3. Integration limits in a finite volume . . . . . . . . . . . . . . . . . . . . . 145
9.4. Resonant antennas in fundamental mode . . . . . . . . . . . . . . . . . . 146
9.4.1. General considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . 146
9.4.2. Wire antennas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
9.4.3. Planar antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
9.4.4. Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
9.4.5. 3D antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
9.5. Bulk reduction techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
9.5.1. Use of dielectrics with strong permittivity . . . . . . . . . . . . . . . 153
9.5.2. Modification of wave path . . . . . . . . . . . . . . . . . . . . . . . . 153
9.5.3. Utilization of inductive, capacitive, and short-circuit effects . . . . 156
9.5.4. Control over radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
9.6. Multiresonant antennas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
9.7. Synthesis and discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
Chapter 10. Reconfigurable Antennas . . . . . . . . . . . . . . . . . . . . . . . 169
Jean-Marc LAHEURTE
10.1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
10.2. Basic topologies and constraints. . . . . . . . . . . . . . . . . . . . . . . 170
10.3. Switched components: available technologies. . . . . . . . . . . . . . . 174
10.4. Frequency reconfigurable antennas (FRAs). . . . . . . . . . . . . . . . 180
10.4.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
10.4.2. Examples of radiating slot-based FRA. . . . . . . . . . . . . . . . . 181
10.4.3. Examples of patch- or PIFA-based FRA integrating
switchable slots. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
10.4.4. Examples of FRA using switched short circuits . . . . . . . . . . . 184
10.4.5. FRA utilizing a loaded stub . . . . . . . . . . . . . . . . . . . . . . . 185
10.5. Introduction to RAs in terms of polarization and
radiation pattern. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
10.6. Polarized reconfigurable antennas (PRAs). . . . . . . . . . . . . . . . . 187
10.7. Radiation pattern reconfigurable antennas (RPRAs). . . . . . . . . . . 190
10.7.1. RPRA with rotational symmetry and switched parasitics. . . . . . 192
10.7.2. RPRA with parasitic elements loaded using
switched reactance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
10.7.3. Unit cell of reflective array based on a patch
of slots [CAD 05]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
Chapter 11. Introduction to Antenna Diversity. . . . . . . . . . . . . . . . . . 205
Lionel RUDANT
11.1. Benefits of antenna diversity. . . . . . . . . . . . . . . . . . . . . . . . . 205
11.1.1. Effects of multipath propagation . . . . . . . . . . . . . . . . . . . . 206
Table of Contents ix
11.1.2. Principles of antenna diversity . . . . . . . . . . . . . . . . . . . . . 207
11.1.3. Non-ideal antenna diversity . . . . . . . . . . . . . . . . . . . . . . . 211
11.2. Performance of multiantenna systems . . . . . . . . . . . . . . . . . . . 214
11.2.1. Antenna balance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
11.2.2. Antenna independence . . . . . . . . . . . . . . . . . . . . . . . . . . 216
11.3. Multiantenna systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
11.3.1. Space diversity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
11.3.2. Compact multiantenna system . . . . . . . . . . . . . . . . . . . . . 224
11.4. Conclusion and looking toward MIMO . . . . . . . . . . . . . . . . . . 228
Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
List of Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
Introduction
This publication covers microwave antennas and more specifically planar
versions, which are the types of antenna preferred at microwave frequencies in
modern integrated communication systems. We see variants of these in everyday
life, hidden away in portable telephones, mobile phone base stations, electronic tags,
or even portable computers. More generally, we see them in all applications
requiring miniaturization and/or a fixed support structure, such as telephone casings.
In terms of this publication, we are therefore not including reflector antennas,
antenna arrays, or more generally directional antennas that occupy a surface or
volume much greater than the wavelength.
Written by a collective of specialist engineers and research professors, this book
is aimed at engineers and researchers who want to:
– understand the principles of planar and/or small volume antennas used in
modern communication systems;
– comprehend the problems of design and manufacture;
– define the constraints and limitations presented by the antenna within the body
of the communication system.
Chapter 1 deals with the physical characteristics of printed antennas (dielectric
support, metallization), manufacturing techniques, and areas of application.
Chapters 2 and 3 describe the so-called transmission line and cavity models,
respectively, of printed antennas. These two models provide complementary
physical interpretations of the basic, usually rectangular geometry of antennas.
These interpretations will apply to more complex yet short depth geometries.
Also we will restrict ourselves to rectangular geometries, to limit the amount of
analysis.