RF AND MICROWAVE ENGINEERING

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5 RF AND MICROWAVE ENGINEERING FUNDAMENTALS OF WIRELESS COMMUNICATIONS Frank Gustrau Dortmund University of Applied Sciences and Arts, Germany A John Wiley & Sons, Ltd., Publication

6 First published under the title Hochfrequenztechnik by Carl Hanser Verlag Carl Hanser Verlag GmbH & Co. KG, Munich/FRG, 2011 All rights reserved. Authorized translation from the original German language published by Carl Hanser Verlag GmbH & Co. KG, Munich.FRG. This edition first published John Wiley & Sons Ltd, Chichester, UK Registered office John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, United Kingdom For details of our global editorial offices, for customer services and for information about how to apply for permission to reuse the copyright material in this book please see our website at The right of the author to be identified as the author of this work has been asserted in accordance with the Copyright, Designs and Patents Act 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, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher. MATLAB is a trademark of The MathWorks, Inc. and is used with permission. The MathWorks does not warrant the accuracy of the text or exercises in this book. This book s use or discussion of MATLAB software or related products does not constitute endorsement or sponsorship by The MathWorks of a particular pedagogical approach or particular use of the MATLAB software. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic books. Designations used by companies to distinguish their products are often claimed as trademarks. All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners. The publisher is not associated with any product or vendor mentioned in this book. This publication is designed to provide accurate and authoritative information in regard to the subject matter covered. It is sold on the understanding that the publisher is not engaged in rendering professional services. If professional advice or other expert assistance is required, the services of a competent professional should be sought. Library of Congress Cataloging-in-Publication Data Gustrau, Frank. [Hochfrequenztechnik. English] RF and microwave engineering : fundamentals of wireless communications / Frank Gustrau. p. cm. Includes bibliographical references and index. ISBN (pbk.) 1. Radio circuits. 2. Microwave circuits. 3. Wireless communication systems Equipment and supplies. I. Title. TK6560.G dc A catalogue record for this book is available from the British Library. Paper ISBN: Typeset in 10/12pt Times by Laserwords Private Limited, Chennai, India

7 For Sabine, Lisa & Benni

9 Contents Preface List of Abbreviations List of Symbols xiii xv xvii 1 Introduction Radiofrequency and Microwave Applications Frequency Bands Physical Phenomena in the High Frequency Domain Electrically Short Transmission Line Transmission Line with Length Greater than One-Tenth of Wavelength Radiation and Antennas Outline of the Following Chapters 8 References 9 2 Electromagnetic Fields and Waves Electric and Magnetic Fields Electrostatic Fields Steady Electric Current and Magnetic Fields Differential Vector Operations Maxwell s Equations Differential Form in the Time Domain Differential Form for Harmonic Time Dependence Integral Form Constitutive Relations and Material Properties Interface Conditions Classification of Electromagnetic Problems Static Fields Quasi-Static Fields Coupled Electromagnetic Fields Skin Effect Electromagnetic Waves Wave Equation and Plane Waves Polarization of Waves 43

10 viii Contents Reflection and Refraction Spherical Waves Summary Problems 55 References 57 Further Reading 57 3 Transmission Line Theory and Transient Signals on Lines Transmission Line Theory Equivalent Circuit of a Line Segment Telegrapher s Equation Voltage and Current Waves on Transmission Lines Load-Terminated Transmission Line Input Impedance Loss-less Transmission Lines Low-loss Transmission Lines Transmission Line with Different Terminations Impedance Transformation with Loss-less Lines Reflection Coefficient Smith Chart Transient Signals on Transmission Lines Step Function Rectangular Function Eye Diagram Summary Problems 106 References 107 Further Reading Transmission Lines and Waveguides Overview Coaxial Line Specific Inductance and Characteristic Impedance Attenuation of Low-loss Transmission Lines Technical Frequency Range Areas of Application Microstrip Line Characteristic Impedance and Effective Permittivity Dispersion and Technical Frequency Range Areas of Application Stripline Characteristic Impedance Technical Frequency Range Coplanar Line Characteristic Impedance and Effective Permittivity Coplanar Waveguide over Ground 128

11 Contents ix Coplanar Waveguides and Air Bridges Technical Frequency Range Areas of Application Rectangular Waveguide Electromagnetic Waves between Electric Side Walls Dominant Mode (TE10) Higher Order Modes Areas of Application Excitation of Waveguide Modes Cavity Resonators Circular Waveguide Two-Wire Line Characteristic Impedance Areas of Application Three-Conductor Transmission Line Even and Odd Modes Characteristic Impedances and Propagation Constants Line Termination for Even and Odd Modes Problems 154 References Scattering Parameters Multi-Port Network Representations Normalized Power Waves Scattering Parameters and Power S-Parameter Representation of Network Properties Matching Complex Conjugate Matching Reciprocity Symmetry Passive and Loss-less Circuits Unilateral Circuits Specific Characteristics of Three-Port Networks Calculation of S-Parameters Reflection Coefficients Transmission Coefficients Renormalization Signal Flow Method One-Port Network/Load Termination Source Two-Port Network Three-Port Network Four-Port Network S-Parameter Measurement Problems 184 References 186 Further Reading 186

12 x Contents 6 RF Components and Circuits Equivalent Circuits of Concentrated Passive Components Resistor Capacitor Inductor Transmission Line Resonator Half-Wave Resonator Quarter-Wave Resonator Impedance Matching LC-Networks Matching Using Distributed Elements Filter Classical LC-Filter Design Butterworth Filter Transmission Line Filter Edge-Coupled Line Filter Hairpin Filter Stepped Impedance Filter Parasitic Box Resonance Waveguide Filter Circulator Power Divider Wilkinson Power Divider Unequal Split Power Divider Branchline Coupler Conventional 3 db Coupler Unequal Split Branchline Coupler Rat Race Coupler Directional Coupler Balanced-to-Unbalanced Circuits Electronic Circuits Mixers Amplifiers and Oscillators RF Design Software RF Circuit Simulators Three-Dimensional Electromagnetic Simulators Problems 246 References 247 Further Reading Antennas Fundamental Parameters Nearfield and Farfield Isotropic Radiator Radiation Pattern and Related Parameters Impedance Matching and Bandwidth 257

13 Contents xi 7.2 Standard Types of Antennas Mathematical Treatment of the Hertzian Dipole Wire Antennas Half-Wave Dipole Monopole Concepts for Reducing Antenna Height Planar Antennas Rectangular Patch Antenna Circularly Polarizing Patch Antennas Planar Dipole and Inverted-F Antenna Antenna Arrays Single Element Radiation Pattern and Array Factor Phased Array Antennas Beam Forming Modern Antenna Concepts Problems 293 References 294 Further Reading Radio Wave Propagation Propagation Mechanisms Reflection and Refraction Absorption Diffraction Scattering Doppler Effect Basic Propagation Models Free Space Loss Attenuation of Air Plane Earth Loss Point-to-Point Radio Links Layered Media Path Loss Models Multipath Environment Clutter Factor Model Okumura Hata Model Physical Models and Numerical Methods Problems 321 References 321 Further Reading 322 Appendix A 323 A.1 Coordinate Systems 323 A.1.1 Cartesian Coordinate System 323 A.1.2 Cylindrical Coordinate System 324 A.1.3 Spherical Coordinate System 325

14 xii Contents A.2 Logarithmic Representation 326 A.2.1 Dimensionless Quantities 326 A.2.2 Relative and Absolute Ratios 327 A.2.3 Link Budget 328 Index 331

15 Preface This textbook aims to provide students with a fundamental and practical understanding of the basic principles of radio frequency and microwave engineering as well as with physical aspects of wireless communications. In recent years, wireless technology has become increasingly common, especially in the fields of communication (e.g. data networks, mobile telephony), identification (RFID), navigation (GPS) and detection (radar). Ever since, radio applications have been using comparatively high carrier frequencies, which enable better use of the electromagnetic spectrum and allow the design of much more efficient antennas. Based on low-cost manufacturing processes and modern computer aided design tools, new areas of application will enable the use of higher bandwidths in the future. If we look at circuit technology today, we can see that high-speed digital circuits with their high data rates reach the radio frequency range. Consequently, digital circuit designers face new design challenges: transmission lines need a more refined treatment, parasitic coupling between adjacent components becomes more apparent, resonant structures show unintentional electromagnetic radiation and distributed structures may offer advantages over classical lumped elements. Digital technology will therefore move closer to RF concepts like transmission line theory and electromagnetic field-based design approaches. Today we can see the use of various radio applications and high-data-rate communication systems in many technical products, for example, those from the automotive sector, which once was solely associated with mechanical engineering. Therefore, the basic principles of radio frequency technology today are no longer just another side discipline, but provide the foundations to various fields of engineering such as electrical engineering, information and communications technology as well as adjoining mechatronics and automotive engineering. The field of radio frequency and microwave covers a wide range of topics. This full range is, of course, beyond the scope of this textbook that focuses on the fundamentals of the subject. A distinctive feature of high frequency technology compared to classical electrical engineering is the fact that dimensions of structures are no longer small compared to the wavelength. The resulting wave propagation processes then lead to typical high frequency phenomena: reflection, resonance and radiation. Hence, the centre point of attention of this book is wave propagation, its representation, its effects and its utilization in passive circuits and antenna structures. What I have excluded from this book are active electronic components like transistors and the whole spectrum of high frequency electronics, such as the design

RF AND MICROWAVE ENGINEERING

RF AND MICROWAVE ENGINEERING FUNDAMENTALS OF WIRELESS COMMUNICATIONS Frank Gustrau Dortmund University of Applied Sciences and Arts, Germany WILEY A John Wiley & Sons, Ltd., Publication Preface List of