Table Of Content

Modern Automotive Antenna Measurements FFoogg--bbooookk..iinnddbb ii 77//2277//22002222 1122::2211::0077 PPMM For a listing of recent titles in the Artech House Antennas Library, turn to the back of this book. FFoogg--bbooookk..iinnddbb iiii 77//2277//22002222 1122::2211::5500 PPMM Modern Automotive Antenna Measurements Lars J. Foged Manuel Sierra Castañer Editors FFoogg--bbooookk..iinnddbb iiiiii 77//2277//22002222 1122::2211::5500 PPMM Library of Congress Cataloging-in-Publication Data A catalog record for this book is available from the U.S. Library of Congress. British Library Cataloguing in Publication Data A catalog record for this book is available from the British Library. ISBN-13: 978-1-63081-849-4 Cover design by Andy Meaden Creative © 2022 Artech House 685 Canton Street Norwood, MA 02062 All rights reserved. Printed and bound in the United States of America. No part of this book may be reproduced or utilized in any form or by any means, elec- tronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without permission in writing from the publisher. All terms mentioned in this book that are known to be trademarks or service marks have been appropriately capitalized. Artech House cannot attest to the accuracy of this information. Use of a term in this book should not be regarded as affecting the validity of any trademark or service mark. 10 9 8 7 6 5 4 3 2 1 FFoogg--bbooookk..iinnddbb iivv 77//2277//22002222 1122::2211::5500 PPMM Contents CHAPTER 1 Introduction to Automotive Antenna and Device Measurements 1 References 4 CHAPTER 2 Challenges and Figures of Merit in Automotive Measurements 7 2.1 Antenna Measurement 7 2.1.1 Antenna Gain and OTA Measurements 8 2.1.2 Calibration Antenna 12 2.1.3 Testing Parameters 14 2.2 NF versus FF Measurements 18 2.3 Introduction to Near Transformation Theory 23 2.4 Radiofrequency System 25 References 27 CHAPTER 3 NFFF Transformations 29 3.1 NF/FF Transformation based on Spherical Wave Expansion 30 3.1.1 SWE 30 3.1.2 Truncated SNF Measurements 43 3.1.3 Advanced SWE Techniques 49 3.2 Equivalent Current Technique 60 3.2.1 Formulation 60 3.2.2 Features 61 3.3 New Methods for NF-to-FF Transformations 63 3.3.1 Sparse Recovery of SWC 64 3.3.2 Optimal Sampling Interpolation 64 References 65 CHAPTER 4 Chamber Design and Analysis 71 4.1 Measurement Ranges 71 v FFoogg--bbooookk..iinnddbb vv 77//2277//22002222 1122::2211::5500 PPMM vi Contents 4.2 Design Criteria 73 4.2.1 Absorbers and Ferrites 73 4.2.2 Rectangular Chambers 76 4.2.3 Tapered Chambers 79 4.2.4 Chambers with Conductive Floors 80 4.3 Analysis Methods 81 4.3.1 Full-Wave Models 81 4.3.2 Ray-Tracer Solvers 81 4.3.3 Image Theory–Based Technique 83 4.3.4 Measurements with the Scaled Model Method 85 4.4 QZ Evaluation with Measurements 90 4.4.1 Field Probe Measurements Over QZ 90 4.4.2 Antenna Pattern Comparison 91 References 93 CHAPTER 5 Implementation and Calibration of Automotive Ranges 97 5.1 Absorber and Conductive Floor Systems 98 5.1.1 Gain Calibration 99 5.1.2 Gain Calibration Accuracy 101 5.1.3 Measurement Examples 103 5.2 FF Ranges 106 5.3 Single-Probe NF Systems 108 5.3.1 Use of Wideband Probes 111 5.3.2 Use of Wideband and Dual-Polarized Probes 114 5.4 Multiprobe NF Systems 120 5.4.1 Probe-Related Design Challenges 121 5.4.2 Sampling in MP Systems 122 5.4.3 Different Implementations of Automotive MP Systems 123 5.4.4 Low-Frequency Measurements 124 5.4.5 High-Frequency Measurements 125 5.5 Scaled Measurements 129 References 131 CHAPTER 6 OTA Measurements 133 6.1 OTA Test Setup 133 6.2 OTA Testing Parameters 134 6.3 OTA System Calibration 135 6.4 OTA Measurement Methods 136 6.4.1 NF to FF Transform Using Phase Recovery 136 6.4.2 Separate Measurements with Conducted RF 137 6.4.3 Two-Step Measurement or Combinational Method 138 6.4.4 Direct OTA Measurements 138 6.4.5 NF to Quasi-FF Transform Through Parallax 139 6.4.6 TRP/TIS Testing of Devices on a Limited Ground Plane 140 FFoogg--bbooookk..iinnddbb vvii 77//2277//22002222 1122::2211::5500 PPMM Contents vii 6.5 OTA Sampling 141 6.6 OTA Measurement Examples 142 6.7 MIMO OTA Testing 146 6.7.1 Introduction 146 6.7.2 Direct MIMO OTA Testing 147 6.7.3 Two-Stage Methods 150 References 151 CHAPTER 7 Advanced Post-Processing Techniques 155 7.1 Post-Processing by the Equivalent Current Method 156 7.1.1 Diagnostics and Filtering 156 7.1.2 Extrapolation of Truncated Areas 158 7.1.3 NF Calculation from the Equivalent Current 160 7.1.4 Link Between Measurements and Simulations 160 7.2 Investigation and Mitigation of Truncation Errors in Free-Space Automotive Systems 163 7.2.1 Case Study Description and Investigation of Truncation Errors Effect 163 7.2.2 Mitigation of Truncation Errors 165 7.3 Free-Space Response Retrieval in PEC-Based Automotive Systems 168 7.3.1 Spatial Filtering Techniques for PEC Removal 168 7.3.2 Example with Scaled Measurements 170 References 174 CHAPTER 8 Virtual Drive Testing 177 8.1 VDT 177 8.2 The Link Between Measurement and Simulation 180 8.3 Simulation of Complex Scenarios from Measurements 181 8.4 Different Ground Emulation of Measured Vehicle Antennas 183 8.5 V2V and V2X Coupling Evaluation 190 References 192 CHAPTER 9 In-Situ Acquisition Systems for Automotive Measurements: Drone and Handheld Approaches 195 9.1 Introduction 195 9.2 Airborne-Based Antenna Measurement Techniques 197 9.2.1 An Overview of Airborne-Based Antenna Measurement Techniques 197 9.2.2 Antenna Characterization by Means of Equivalent Currents 199 9.2.3 Application Example 202 9.3 Handheld Systems 208 9.3.1 An Overview of the Handheld System 208 9.3.2 Handheld System Description 208 FFoogg--bbooookk..iinnddbb vviiii 77//2277//22002222 1122::2211::5500 PPMM viii Contents 9.3.3 Particular Characteristics of the Handheld System 210 9.3.4 Application Example 212 9.4 Final Remarks 213 References 216 CHAPTER 10 Practical Aspects of Automotive Measurements and Virtual-Drive Testing 221 10.1 Challenges for Automotive Antenna Measurements 221 10.1.1 Limitations of Automotive Antenna Measurement Range 221 10.1.2 Implications of the Car Body for Antenna Design and Measurements in the Installed State 225 10.2 Application-Oriented Post-Processing of Automotive Antenna Measurements 229 10.2.1 Phase Center Determination 229 10.2.2 Automotive Antenna Performance Indicators 232 10.3 Over-the-Air Vehicle-in-the-Loop Approach for System Validation in a Virtual Environment 234 10.3.1 Concept 234 10.3.2 LTE and V2X Emulation 236 10.3.3 Automotive Radar 240 References 246 About the Editors 253 About the Contributors 254 Index 259 FFoogg--bbooookk..iinnddbb vviiiiii 77//2277//22002222 1122::2211::5500 PPMM CHAPTER 1 Introduction to Automotive Antenna and Device Measurements Lars J. Foged and Manuel Sierra Castañer Antenna and electromagnetic characterization have been challenging topics for more than 50 years. Antenna measurements are commonly an evaluation of the radiation properties in the far field (FF), assuming that the antenna or device origin is positioned at an infinite distance from the observation point. The FF condition is also often referred to as plane wave condition since radiation tends to approximate a plane wave at infinity. Far from its origin, electromagnetic radiation will have spread out enough that it will appear to have uniform amplitude and phase on a plane perpendicular to its direction of travel. Thus, at sufficient distances, an antenna will appear to radiate plane waves in all directions. Due to reciprocity, the FF radiation of an antenna can also be measured by exposing the entire antenna locally to an approximate plane wave as shown in Figure 1.1. Thriving to perform the measurements in sufficiently good approximation to FF condition is a paradox since a major part of communications supported by antennas and devices with antennas occurs at a finite distance and often in the near Figure 1.1 Example of automotive measurement by exposing the vehicle-mounted antenna to an approximate plane wave. 1 FFoogg--bbooookk..iinnddbb 11 77//2277//22002222 1122::2211::5500 PPMM