( Oc, NAVIGATION f< Edited by JOHN S. HALL, PH.D. ASSOCIATE PFIOFESSOEI OF ASTRONOhfY AND PHYSICS AMHF.FIST CO1.l,EGE OFFICE OF SCIENTIFIC RESEARCH AND DEVELOPMENT N.kTIONAL D13F131vSE RESE.iRCH COMIIITTEE FmsT EDITION NEW YORK AND I.ONDOIV kflcGRAw -HILL BOOK COMPANY, INC 1947 ‘i ,M4/ Vi-z C3 R.41).+R .UI)S T(3 XAVIGA’IYON COpyRIGFtT, 1!)47, B~-THE \IrCJRIW-HILL BOOK CnMP.\xI-. INC. PRINTEI) IX THE UNITED SrI~.4TES OF .kMliRICA .111lights resewed Y’his book. or Paris thereof, m ynot bcreproduced in on!i form 7uithtI;[(pennissim of the publishers. THE MAPLE PRESS COMPANY, YORK, PA. ,.. . .....”... ‘<. . L, MASSACHUSETTS INSTITUTE OF TECHNOLOGY RADIATION LABORATORY SERIES BoardofEditors LouIs N. RIDENOUBE,ditor-in-Chief GEORGE B. COLLINS, Deputy Editor-in-Chief BEITTONCHANCES,.A.GOUDSMIRT.,G.HERB,HUBEETM.JAMESJ,ULIANK.KNIPP JAMESL. LAWSON, LEON B. LINFORD, CAROL G. MONTGOMERCY.,NEWTONA,LBEIW M. STONEL,ouIs A. TURNERG, EORGEE. VALLEY,JR.,HERBERT H. WHEATON 1. RADAR SYSTEMENGINEERING—Ridenour 2. RADAR AIDS TONAVIGATION—HU21 3. RADAR BEAcoNs—Roberls 4. LoRAN—Pierce, McKenzie, and Woodward 5. PULSE GENERATORS-6%S0e and Lehacqz 6. MICROWAVE MAGNETRONS—CO/~~nS 7. KLYSTRONS AND MICROWAVE TR1oDEs—Hamillon, Knipp, and Kuper 8. PRINCIPLES OF MICROWAVE (%icuITs—Monigo?nefg, Dicke, and Purcell 9. MICROWAVE TRANSMISSION CIRCUITS—hkgan 10. WAVEGUIDE HANDBooK—Mamwilz 11. TECHNIQUE OFMICROWAVE MEAsURE~ENTS—Mon@0mt7~ 12. MICROWAVE ANTENNA THEORY ANDDEsIGN—Sike?’ 13. PROPAGATION OFSHORTRADIO WAvES—Kt?m’ 14. MICROWAVE DUPLEXERS—S~U~/in and Montgomery 15. CRYSTAL RECTIFIERS—~0f7e~ and Whitmer 16. MICROWAVE MIXERs-.?ounU 17. COMPONENTSHANDEooK—BLackhurn 18. VACUUM TUBE AMPLIFIERS— Valle~ and Wallman 19. WAVEFORMS—ChUn03, Hughes, ,lfac.Vichol, i+zyre, and wdliam& 20. ELECTRONIC TIME MEASUREMENTS—Chan@ Hulsizer, MacNachoL, and Williams 21. ELECTRONIClNsTRuMENTs+Teenuood, Holdam, and MacRae 22, CATHODERAYTUBE DISPLAYS—~o~kr, slaw, and Valley 23. MICROWAVE RECEIVERS—Van Voorhis 24 THRESHOLD&GNAI,s—Lawson and Uhlenheck 25 THEORY OFSERVOMECHANISMS—Ja771.3SN,ichols, and Phillips 26 RADAR SCANNERSANDRAuoMEs—Cady, Karelifz, and Turner 27 COMFLITINGMECHANISMSANDLINitAGES-&JObOd@ 28 IrwEx–Henne~ o Foreword THEtremendous research and development effort that went into the development of radar and related techniques during World War II resulted not only in hundreds of radar sets for military (and some for possible peacetime) use but also in a great body of information and new techniques in the electronics and high-frequency fields. Because this basic material may be of great value to science and engineering, it seemed most important to publish it as soon as security permitted. The Radiation Laboratory of MIT, which operated under the super- vision of the National Defense Research Committee, undertook the great taskofpreparing these volumes. The work described herein, however, is the collective result of work done at many laboratories, Army, Navy, university, and industrial, both in this country and in England, Canada, and other Dominions. The Radiation Laboratory, once its proposals were approved and finances provided by the Office of Scientific Research and Development, chose Louis N. Ridenour as Editor-in-Chief to lead and direct the entire project. An editorial staff was then selected of those best qualified for thistype oftask. Finally the authors for thevarious volumes orchapters or sections were chosen from among those experts who were intimately familiar with the various fields, and who were able and willing to write the summaries of them. This entire staff agreed to remain at work at MIT for six months or more after the work of the Radiation Laboratory wascomplete. These volumes stand as a monument to this group. These volumes serve as a memorial to the unnamed hundreds and thousands of other scientists, engineers, and others who actually carried on the research, development, and engineering work the results of which arehereindescribed. There weresomany involved inthis work and they workedso closely together even though often in widely separated labora- toriesthat itisimpossible to name oreven to know those who contributed toaparticular idea ordevelopment. Only certain ones who wrote reports orarticles have even been mentioned. But to all those who contributed inany way to this great cooperative development enterprise, both in this country and in England, these volumes are dedicated. L. A. DUBRInGE RADAR AIDS TO NAVIGATION EDITORIAL STAFF L. A. TURNER, TECH. ED. J. S. HALL, ED. R. M, WHITMER, ASS’T. ED. CONTRIBUTING AUTHORS H. B. ABAJIAN D. B. MCLAUGHLIN F. R. BANKS, JR. R. E. MEAGHER J. H. BUCK E. E. MILLER W. M. CADY R. H. MULLER M. A. CHAFFEE J. P. NASH G. C. COMSTOCK C. F. J. OVERHAGE D. DAVIDSON J. A. PIERCE R. M. EMBERSON J. B. PLATT A. G. EMSLIE R. M. ROBERTSON H. FAHNESTOCK,JR. E. L. SINSHEIMER G. A. GARRETT C. A. SMITH D. L. HAGLER H. P. STABLER J. S. HALL J. M. STURTEVANT D. HALLIDAY W. J. TULL J. J. HIBBERT L. A. TURNER N. W. MACLEAN T. H. WATERMAN R. M. WHITMER )v * 1 Preface Radar Aids toNavigation isintended primarily to describe the advan- tages and limitations of radar equipment when applied to problems of navigation and pilotage, whether the equipment is airborne, shipborne, orground-based. Radar beacons asaidsto navigation arealsodismmed. While the development of radar was proceeding apace under the impetus of the Second World War, the development of ahost of nonradar navigational aids was also accelerated. These aids include systems that measurerange differences like Loran and Gee and a number of azimuthal systems like the German Sonne. Descriptions of these and other non- radar aids are included to give the reader a more comprehensive picture of available techniques. The authors have not always found it possible to present this informa- tion in a nontechnical form. The reader with no technical background should obtain a fair estimate of the value of radar in navigational prob- lemsfrom Chaps. 2,3, 8, and 9. Radar indicators are described in some detail in this volume because, of all the components, they are of greatest interest to the navigator. A more detailed discussion of many of the engineering problems mentioned here is given in Radar System Engi- neering, Vol. 1 of this series. In thk volume, the emphasis is placed more on what can now be done with radar than on what should be possible in the future. A pos- sible exception to this policy is the inclusion of several photographs of airborne radar indicators attached to radars with antenna beams 0.8° wide. Although these pictures illustrate what can now be done, beam- widths of 3° to 5°, rather than 0.8°, appear practical for airborne radars to be used as navigational aids in the near future. More emphasis has been placed on airborne radar used with beacons as an anticollision device on overwater flights simply because it does not appear reasonable to require that all airplanes flying over land have beacons. A real effort has been made to define terms either explicitly or by their use. A certain amount of repetition results from this policy. For most radar applications described here, narrow antenna beams neces- sitating short wavelengths, or microwaves, are commonly prescribed. By J PREFACE thk term is meant radio waves between 1 and 12 cm long. It is not our intention to insult the reader’s intelligence by defining words found in a small dictionary, nor even the word radar. There is no glossary. The definitions of many words may be found by reference to the index. Thirty-three authors and many persons serving in other capacities have contributed to this book. Unfortunately it is not practical to give full acknowledgement to everyone. R, A. Whitmer, assistant editor, did a large share of the editorial work connected with the portion of the book devoted to airborne radar. L. A. Turner, technical editor, was amost constructive influence in clarifying many sections. His criticisms and suggestions were invariably followed. R. G. Herb served as technical editor during the formative stage of this project. David Davidson deserves a solid vote of thanks for selecting the illustrations used inthe sections onLoran and other navigational nets and for writing their captions. We are grateful also to M. G. White, D. T. Griggs, and R. J. Dippy for their criticism. We regretted to learn that illness prevented Dippy, the originator of Gee, from sending us a description of the miniature system similar to Gee that the British have recently used successfully as an airport approach system. Thanks are due to L. J. Laslett, R. M. Emberson, G. C. Comstock, M. A. Chaffee, and J. H. Buck for assistance in making the original outlines of the book. We are grateful to Beka Doherty who, as an uninhibited reader, read the final manuscript and made many helpful criticisms and suggestions. We acknowledge with thanks the careful manner in which Louise Butler, our production assistant, guided the diagrams and photographs to their ultimate completion. A large amount of secretarial work con- nected with the book was cheerfully done by Bernyce Goldberg. Thanks aredue to Eleanor Uhl who acted as editorial assistant during the forma- tive stages of the book and particularly to Barbara Rudolph who bravely shouldered this responsibility during its critical final stages. JOHN S. HALL. CAMERIDGME,ASS., June,1946. r Contents FOREWORD BYL. A. DUBRIDGE . . . vii PREFACE . . . . . . . . . . . . . . .,, . . . . . . . . . . . . ..ix PART I. INTRODUCTION CHAP.1. PRINCIPLES OF RADAR... . . . . . 3 HOWRADARWORKS, ..,... . . . . . . . . . . . ..3 1.1. The Fundamental Ideas. . . . . . 3 1.2. Resolution, Accuracy, and Coverage. . . . . . 10 1.3. Design Considerations. . . . . . . 15 PROPAGATION. . . . . . . . . . . . . . . . . ..21 1.4. Curvature of the Earth and Atmospheric Refraction, . . 21 1.5. Atmospheric Attenuation . . . . . . . . 22 INDICATORS. . . . . . . . . . . . . . . . . . . . . ..26 1.6. Cathode-ray Tubes .,.,, . . . . . . . . . . . . ...26 1.7. Synchros, Servomechanisms, and Amplidynes. 28 1.8. Different Types of Indicators. . . . 30 RADARBEACONS.....,,, . . . . . . . . . ,,36 1.9. Operation...,,,,. . . . . . . . .36 1.10. Future Developments; Systems. 41 CHAP.2. NONRADAR NAVIGATIONAL METHODS . . 44 2.1, Nonradar Navigational ~Methods . . 44 2,2. Radio Ranges .,...,, . . . . . . . . . . . . ...44 2.3. German Radio Rangej Sonne, 47 2.4. Ultri+hlgh-frequency, Navigational Aids, uhf. . 50 2.5. Airborne and Shipborne Direction Finders . 51 2.6, Ground Direction Finders . . . . . . . 54 2.7. Celestial Navigation. . . . , 55 LOEANmn OTHERNAVIGATIONAL NETS . . . . . . . . . . 56 2.8. Hyperbolic Systems . . . . . . . . . . . . . . . 56 2.9. Gee. . . . . . . . . . . . . . . . . . . . . . . . ...60 210.Loral . . . . . . . . . . . . . . . . . . . . . . . ...64 2.11. ’’SLoranr,n .,..,,., . . . . . . . . . . . . ...70 2.12. Low-frequency Loran..., . . . . . . . . . . . . . . . 72 2.13. Mecca. . . . . . . . . . . . . . . . . . . . . . . ...76 CONTENTS 2.14. AccuracyandRangeofVariousHyperbolicSyeteme.. . . . . 77 2.15. Autimatic Data ~alysis .-‘. . . . . . . . . . 79 2.16. Automatic Piloting . . . . . . . . . . . . . . . . . . 82 PART 11. AIRBORNE RADAR CHAP. 3. CHARACTERISTICS OFAIRBORNE RADAR. . . . . . . . . 89 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 3.1. FeaturesRevealedby RadarMapping. . . . . . . . . . . 89 3.2. DetailsinRadarMapping. . . . . . . . . . . . 96 3.3. TbeOperator. . . . . . . . . . . . . . . . . . . . . . . 105 3.4. MeasurementofDriftandGround%eed . . . . . . . . 105 3.5. Determination of Drift and “Ground Speed”GverWater. . . 110 3.6. InfotrnationAvailableonFlightsOverWater. . . . . . . . 112 3.7. TbeUseofMapaseAidstoRadarPilotage. . . . . . 115 3.8. RadarBeaconNavigation . . . . . . . . . . . . . . . 117 (%AP. 4. SPECIAL AIDS AND DEVICES. . . . . . . . . . . . . . . . 122 NAVIGATIONArm ANTICOLLISION . . . . . . . . . . . . . . . . . . 122 4.1. The Ground Position Indicator. . . . . . . . . . . . . . . 122 4.2. AnticolliAon Radar Devices . . . . . . . . . . . . . . . . 128 Armrrmm DETERMINATION. . . . ,.. . . . . . . . . . . . 131 4.3. Pulsed Radio Altimeters (SCR718C) . . . . . . . . . . . 132 4.4. Frequency-modulated Altimeters (AN/APN-1)’. . . . . . . . 136 4.5. Comparison of F-m and Pulsed Altimeters. . . . . . . . . . 141 4.6. Suggested Future Trends. . . . . . . . . . . 142 CMP. 5. SPECIAL DESIGN CONSIDERATIONS. . . . . . . . . . . 143 5.1. Receivere . . . . . . . . . . . . . . . . . . . . . ...143 5.2. Indicatore . . . . . . . . . . . . . . . . . . . . . ...148 5.3. Antennaa . . . . . . . . . . . . . . . . . . . . . ...155 6.4. Antenna Stabilization . . . . . . . . . . . . . . . . ...156 CHAP. 6. ENGINEERING AND ECONOMIC CONSIDERATIONS. . . . 161 6.1. Installation . . . . . . . . . . . . . . . . . . . . . ...161 6.2. General Design Considerations . . . . . . . . . . . . 165 6.3. Performance of AN/APS-10. . . . . . . . . . . . . 171 6.4. Characteristics of the AN/APS-10 Radar:I . . . . . . . . . 174 6.5. CharacteristicsoftheAN/AP~10 Radar:II. . . . . . . . . 181 6.6. TypicalPerformanceofSomeExistingSystems. . . . . . . 185 6.7. EconomicAspectsofAirborneRadar . . . . . . . 187 PART III. GROUND-BASED RADAR CHAP.7. TYPES OF GROUND-BASED RADAR AND SPECIAL EQUIP- MENT . . . . . . . . . . . . . . . . . . . . . . . . ...193 SEARCH mm AUTOMATIC-TRACKKNCJRADARS. . . . 193 7.1. A Long-range Microwave System. . 193 7.2. Automatic Tracking Systems. . 202 CONTENTS HEIGHTFINDERS, ,,, . . . . . . . . . . . . . . . . . . . . 207 7.3. Height-finding Methods . . . . . . . . 207 7.4. General Problems of Design . . . . . . . . . 212 7.5. Illustrations of Some Recent Systems . . . . . . . . 218 RADAEAIDS FORLANDING . . . . . . . . . . . . . . . . . . . 227 7.6. Beam Approach Systems. . . . . 227 7.7. Beacon Approach Systems, BABS . . . . 232 7+3. Ground-based Scanning Radar Systems . . . . . 237 SPECIALRADLRALDS . . . . . . . . . . . . . . . . . . . . 252 7.9. Moving Target Indication . . 252 7.10. Beacons . . . . . . . . . . . . . . . . . . . . . . ...256 7.11. Radar Relay . . . . . . . . . . . . . . . . . . . . ...258 7.12. Video Mapping . . . . . . . . . . . . . . . . . . . ...267 7.13. Radar Aids to Mapping . . . . . . . . . . . . . . . ...278 @P. 8. RADAR AIDS TO AIR NAVIGATION AND TRAFFIC CONTROL 285 81. Statement of the Problem 285 8.2. Navigation and Traffic Control Using Airborne Radar Aids 293 8.3. Navigation and Traffic Control Using Ground-based Radar Aids 299 &4. Sum~ary of Proposed Aids. ~. . . 311 PART IV. SHIPBORNE RADAR CnAP.9, NAVIGATIONAND PILOTAGE 317 9.1. How Radar Can Help the Navigator 317 9.2. Coordination of Radar Data with Other Data 320 9.3. Marine Radar Beacons. .322 9.4. Corner Reflectors . . . . . . . . . . . .324 9.5. Principle of Superposition h’avigation . 331 9.6. Char&matching Equipment . 335 9.7. Accuracy Obtainable by Chart Matching. . . . . 344 9.8. PPISlmulations, ,., . . . . . . . . . . . . . . ...351 BIBLIOGRAPHY. . . . . . . . . . . . . . . . . . . . . 353 Crop. 10. A SHIPBORNE NAVIGATIONAL RADAR . . . 354 10.1.Radar Propagation over Water, . 354 102. General Specifications of a Shipborne Navigational Radar 363 10.3,Anterma Assembly . . . . . . . . . . . . . . . . . ...364 10.4.Transmitter-receiver Package. 371 10.5.Indicator . . . . . . . . . . . . . . . . . . . . . . ...373 106. Power Supply . . . . . . . . . . . . . . . . . . . ...377 10.7.Physical Characteristics of the Components and Test Equipment 379 INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383 i