Technical and Military Imperatives A Radar History of World War II Related Titles Cockcroft and the Atom G Hartcup and T E Allibone (out of print) Operation Epsilon: The Farm Hall Transcripts Edited by Sir Charles Frank Radar Days E G Bowen Echoes of War: The Story of H2S Radar Sir Bernard Lovell Boffin: A Personal Story of the Early Days of Radar and Radio Astronomy and Quantum Optics R Hanbury Brown Heavy Water and the Wartime Race for Nuclear Energy P F Dahl Electronic Inventions and Discoveries G W A Dummer Technical and Military Imperatives A Radar History of World War II Louis Brown Carnegie Institution of Washington Washington DC, USA 1999 Institute of Physics Publishing Bristol and Philadelphia c 1999 IOP Publishing 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 permission of the publisher. Multiple copying is permitted in accordance with the terms of licences issued by the Copyright Licensing Agency under the terms of its agreement with the Committee of Vice-Chancellors and Principals. The author has attempted to trace the copyright holders of all the figures reproduced in this publication and apologizes to them if permission to publish in this form has not been obtained. British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library. ISBN 0 7503 0659 9 Library of Congress Cataloging-in-Publication Data are available Production Editor: Jacky Mucklow Production Control: Sarah Plenty and Jenny Troyano Commissioning Editor: Jim Revill Editorial Assistant: Victoria Le Billon Cover Design: Kevin Lowry Marketing Executive: Colin Fenton Published by Institute of Physics Publishing, wholly owned by The Institute of Physics, London Institute of Physics Publishing, Dirac House, Temple Back, Bristol BS1 6BE, UK US Office: Institute of Physics Publishing, Suite 1035, The Public Ledger Building, 150 South Independence Mall West, Philadelphia, PA 19106, USA Typeset in TEX using the IOP Bookmaker Macros Printed and bound in the UK by Cambridge University Press, Cambridge CB2 2BS CONTENTS PREFACE WITH ADVICE TO THE READER ix ACKNOWLEDGMENTS xiii 1 PRELIMINARIES 1 1.1 Radio vision for war 1 1.2 Electromagnetic waves 6 1.3 Perceptions of air power, 1919–1939 11 1.4 Navigation in 1939 19 1.5 Anti-aircraft artillery, 1914–1939 23 Photographs: Preliminaries 30 2 ORIGINS 33 2.1 Electronic component development 33 2.2 Beginnings, 1902–1934 40 2.3 Britain builds an air defense system 49 2.4 Americans and Germans build prototypes 64 2.5 Five other nations 83 Photographs: Air warning—Europe 92 3 FIRST CLASHES 97 3.1 War in Europe 97 3.2 The Battle of Britain and the Blitz 107 3.3 The Atlantic, 1941 120 3.4 Friend, foe or home? 129 3.5 The Japanese realize they are behind 135 Photographs: Air warning—Pacific 141 4 NEW IDEAS 145 4.1 Microwaves 145 4.2 The Tizard Mission 159 4.3 The Radiation Laboratory 166 4.4 The proximity fuze—the smallest radar 174 4.5 Greater and lesser microwave sets 186 Photographs: Land and naval fighter control 198 Technical and Military Imperatives 5 YEARS OF ALLIED DESPAIR AND HOPE 205 5.1 The Mediterranean, 1940–1942 205 5.2 War in the Pacific 215 5.3 The Channel, 1942 224 5.4 Carrier warfare defined 235 5.5 The South Pacific, 1942 246 5.6 The Eastern Front 262 Photographs: Naval radar 270 6 THE GREAT RADAR WAR 279 6.1 The destruction of German cities initiated 279 6.2 Countermeasures 290 6.3 An air war of attrition 300 6.4 Arbeitsgemeinschaft Rotterdam 310 6.5 The destruction of German cities completed 317 Photographs: Radar for AA artillery 326 7 ALLIED VICTORY IN SIGHT 334 7.1 The Battle of the Atlantic, 1939–1945 334 7.2 Radar in arctic waters 348 7.3 The Mediterranean, 1943–1945 353 7.4 Japanese shipping destroyed 359 7.5 The wide Pacific 367 Photographs: Airborne radar 382 8 THE END IN EUROPE 386 8.1 Invasion 386 8.2 Flying bombs 392 8.3 The battlefield transformed 398 8.4 Post mortem 403 Photographs: Tubes 409 9 THE END IN ASIA 411 9.1 The Philippines and Okinawa 411 9.2 The destruction of Japanese cities 420 10 THE MEASURE OF RADAR 427 10.1 Navigation transformed 427 10.2 Science and the electronic age 433 10.3 Secrecy and the technical imperative 444 10.4 An evaluation 456 APPENDIXA: A FEW RADAR ESSENTIALS 466 A.1 Electromagnetic waves 466 A.2 Reflected signals 468 A.3 Antennas 469 A.4 Lobes 471 A.5 Vertical lobe structure 471 vi Contents A.6 The Yagi antenna 473 A.7 Electron tubes 473 A.8 Transmitters 475 A.9 Receivers 475 A.10 Indicators 476 NOTES AND SOURCES 479 BIBLIOGRAPHY 524 NAME INDEX 533 SUBJECT INDEX 544 vii PREFACE WITH ADVICE TO THE READER This book is about science and war. These are unquestionably the two most dissimilar manifestations of the behaviors that distinguish man from beast. Science—allow it here to mean all elements of our search to understand the universe and put that understanding to use—is the most remarkable of human occupations. It is also the most important. For us not to strive to understand the universe would be as foolish as for castaways not to explore the island on which they find themselves. Science, like art and literature, draws from the mind those inner, intangible feelings which we flatter ourselves give us our station on Earth. It discloses to us things of unparalleled beauty and wonder—the mathematical beauty of the laws of physics, the wonder that life is understandable. War is the negation of all this. It is a disease, like smallpox, that must be eradicated. Yet war is almost as unique to man as is science. Other than ourselves, only ants organize their violence so that it can be called war. Violence is ubiquitous to the biological world, but it is man’s doing to make it an inner- most part of civilization. War is the great embarrassment of civilization, yet all great civilizations have maintained themselves by their military skills and have vanished when those skills no longer sufficed to protect them or sustain internal order. Moreover, from the dawn of civilization science and war have been inseparable companions, locked in a partnership that neither desires and that neither is capable of dissolving. No one setting out to read this book needs the recitation of a catalog of invention and discovery that bears on military history to be convinced of science’s significance, but if this relationship is so well known, what is the purpose of this book? It has a void to fill, for an important element in this story is not well told. Years ago I was struck by the absence of a comprehensive and international history of radar, of the kind that has appeared many times about the atomic bomb. Not that there were no books on the subject; on the contrary, there is almost an over-abundance, as the numerous references cited herein attest. There are among them some extremely good accounts of various parts of the story, and it is my hope that this study will impel many to read them for the things I have had to ix Technical and Military Imperatives leave out. However, these histories are all parochial, for they invariably found their origins in the personal involvement of the authors in radar or on material gleaned from national or laboratory sources. The secret nature of radar did not give the engineers, scientists and military much chance to learn what took place on the other side of the hill, so national versions tell one little about other countries and all too frequently leave the reader with a distorted impression of the whole subject. This does not imply dispute about the facts. The German and British accounts each emphasize the development of their own equipment, of course, but describe the great radar struggle between the Luftwaffe and RAF Bomber Command without significant disagreement. They leave the curious impression, however, that World War II was a private fight between Britain and Germany. There were in America four large radar development laboratories of comparable importance. The histories written about them are quite un- equal and show poor understanding of the contributions of others. Three years into the project I was still encountering major surprises that changed my understanding in a substantive way. Most radar histories trace its ori- gins to a few relatively well known and oft reported events. It has not taken any great depth of scholarship to recognize that radar was just in the air during the 1920s and 1930s. This is obvious when one learns that eight nations had radar projects in 1939. There is evidence that leads one to suspect that hundreds of communication engineers observed reflection and interference phenomena causing them to think about radio location without recording it. The strong similarities of the German and American programs alone speak volumes for its invention being a technical impera- tive. ‘The bomb may have ended the war but radar won it.’ This was the comment of many radar workers in August 1945, when the news of the atomic bomb upstaged the release of public knowledge of the MIT Radiation Laboratory, planned as a cover story for Time. This statement has been repeated many times since then, often with categorical statements concerning some engagements, but has never been examined for the war as a whole.