694 BELL SYSTEM TECHNICAL JOURNAL 



Variable Range Marker Circuits 793 



2.7 Automatic Frequency Control and Automatic Gain Control 800 



2.71 Automatic Frequency Control 800 



Function and Requirements 802 



AFC Circuit Design Considerations 804 



Typical AFC Circuit Designs 805 



2.72 Automatic Gain Control 809 



2.8 Radar Receiver Power Supplies 810 



2.81 Primary Power Sources 810 



2.82 Low Voltage Power Supplies 811 



2.83 High Voltage Power Supplies 814 



Conclusion 816 



Introduction 



THE spectacular development of radar during World War II remains 

 an outstanding achievement in the history of communications and the 

 allied electronic sciences. With military necessity furnishing the required 

 driving force and through the full interchange of technical knowledge among 

 all interested workers in this field, it has been possible to extend our visual 

 senses far beyond the horizons considered quite inelastic only a few years 

 ago. The potentialities of radar in the peacetime world and the future 

 application of radar design principles and techniques to the communications 

 and allied fields justify a review of some further details of this wartime de- 

 velopment. 



The performance and design aspects of radar receivers will be considered 

 in this paper. For this purpose, the radar receiver will be defined as that 

 assemblage of components within the radar system which is required to 

 detect, amplify, and present the desired information as gathered at the radar 

 location. The input signals to the radar receiver consist of radio-frequency 

 pulses containing information regarding the area under observation by the 

 radar system, together with coordinate data defining further characteristics 

 of this observed area. The output of the radar receiver is most commonly 

 an optical presentation of this composite information, but in certain appli- 

 cations the output is further converted into electrical or mechanical signals 

 for specific use. In general, the output of a radar receiver is presented in a 

 form capable of immediate analysis and use. 



Though the functional boundaries of the radar receiver are by the above 

 definition quite distinct, the e.xact detailed composition of the receiver and 

 the specific component designs are influenced by a considerable number of 

 factors. The successful performance of a radar receiver is dependent to a 

 large degree on the nicety with which these individual components are 

 assembled into the system as a whole. 



A study of the principal factors which influence the design of the radar 

 receiver is j^resented in the following sections, followed by a more detailed 

 exposition of the principal design aspects of the various components associ- 

 ated within the receiver. Illustrative equipment descriptions arc included 



