THE RADAR RECEIVER 695 



where military security permits. All of the specific equipment examples 

 presented here have been chosen from radar systems that have been de- 

 veloped within the Bell Telephone Laboratories and manufactured for the 

 services by the Western Electric Company. This latter limitation excludes 

 many interesting experimental developments w^hich have not been produced 

 in quantity and which have not, therefore, been substantially employed by 

 the services during the war period. 



It should be observed that the rapid development and successful employ- 

 ment of radar systems during World War II have come about through the 

 cooperation and coordination of various governmental and military agencies, 

 many research and development organizations, and countless individual 

 workers. It is, therefore, an impossible task to assign individual credit for 

 the details of the development which is here described. Radar has reached 

 its present state of development through the efforts of many, not only those 

 employed specifically on radar projects during the war years, but also those 

 technical workers in the communications and allied fields in the years prior 

 to the war who so adequately supplied the firm basic foundation upon which 

 to build. 



1. Radar Receiver Design Considerations 

 1.1 The Military Radar System 



The specific use and area of operation of the radar system are two basic 

 factors which exercise a profound influence on the receiver design. It is, 

 therefore, pertinent to consider some common classifications of radar sys- 

 tems as employed during the war years. 



A convenient functional classification of military radar systems may be 

 made as follows: 



A. Search or Navigation 



This classification may include warning of the presence of enemy surface 

 vessels or aircraft, navigation by location of landmarks, and reconnaissance. 



B. Missile Control 



This function includes radar systems to control gunfire and release bombs 

 or missiles. 



C. Aircraft Interception 



This classification may be considered as an airborne combination of search 

 and missile control, but is separated here because of the special radar design 

 problems encountered. 



As the detailed electrical performance requirements are primarily in- 



