PREFACE 



THE MATERIAL presented in this boolc was pre- 

 pared by the Cohimbia University Wave 

 Propagation Group at the request of the Committee 

 on Propagation of the National Defense Research 

 Committee. The International Radio Propagation 

 Conference, meeting at Washington in May 1944, 

 recommended that a boolc be prepared dealing with 

 problems of radio wave propagation in the standard 

 atmosphere at frequencies above 30 megacycles. 

 The importance of these higher frequencies is 

 apparent when it is recalled that most radars operate 

 in this range and that an increasing number of 

 communication circuits are being equipped for 

 operation above this frequency. 



A certain amount of evidence from operational 

 theaters indicates that lack of familiarity with the 

 underljdng theory of propagation and calculations 

 based thereon not infrequently has resulted in 

 ineffective installation and operation of radar and 

 communication sets. This is ascribable, in part at 

 least, to the lack of publications which give a clear 

 picture of the problems of propagation or show how 

 the important factors may l^e evaluated. 



A considerable volume of basic material on 

 propagation had appeared in technical jom-nals 

 before World War II, and during it a great quantity 

 of classified material has come from laboratories and 

 operational theaters illustrating new applications of 

 old principles, giving valuable information on propa- 

 gation problems as well as on characteristics of 

 radar and communication sets, antennas, targets, 

 siting problems, etc. But this information has not 

 been coordinated under one cover for practical use 

 by signal personnel in the field. The Columbia 

 University Wave Propagation Group was asked to 

 undertake this task and it is hoped that tliis book 

 will, in some measure, answer the need. 



Our effort, then, has been to provide a book de- 



signed for men with college training in radio, physics, 

 or electrical engineering, which states the basic laws 

 of propagation, that is, shows how the characteristics 

 of the earth and the atmosphere control the propaga- 

 tion of radio waves; gives the fundamental properties 

 of the basic types of antenna systems, particularly 

 their directivity and gain; gives the reflecting 

 properties of targets such as airplanes for use in 

 detection by radar; teaches the reader how to calcu- 

 late field strength or obtain the coverage diagrams 

 given a particular set, power, and site; gives the 

 fundamental information required in the above 

 calculations for application to the radar and com- 

 munication sets used in operational theaters; and 

 provides illustrative material and sample calcula- 

 tions which show how the laws of propagation may 

 advantageoush' be used in the location and operation 

 of radar S3'stems, communication sets, and counter- 

 measure equipment designed to deceive the enemj^ 

 and to prevent jamming of equipment by enemj^ 

 action or by mutual interaction of our own sets. 



The members of the group chiefly responsible for 

 the preparation of the manuscript were Drs. S. 

 Rosseland, W. M. Elsasser, P. Newman, and 

 Prof. S. Fich. Others who contributed special sec- 

 tions were Messrs. E. R. Wicher, M. Ettenberg, 

 M. Siegel, and Capt. E, J. Emmerling, on special 

 assignment from the Signal Corps. 



The editor wishes to acknowledge also the courtesy 

 of the Radiation Laboratory Wave Propagation 

 Group, under Mr. Donald E. Kerr, in supplying the 

 universal coverage charts given in Chapter 6, and 

 the steady interest and assistance rendered by 

 Dr. Chas. R. Burrows, Chairman, NDRC Com- 

 mittee on Propagation. 



Stephen S. Attwood 

 Editor 



