1-4] FUNCTIONAL CHARACTERISTICS OF RADAR SYSTEMS 



Rfwp = ^(/f cos L 

 Rfwn = y^tf sin L 

 Equating components, we obtain the basic fire-control equations 

 VqIj cos L = R — Rtf (time of flight equation) 



_R^ 



(lead angle equation). 



9 

 (1-8) 



(1-9) 



(1-10) 

 (1-11) 



Mapping. The microwave energy scattering characteristics of 

 physical objects provide a wide range of characteristic returns. The 

 differences between these returns make it possible to use a radar system to 

 obtain a map of a given area and permit the interpretation of the results 

 through an understanding of the characteristic returns. The mapping 

 function is accomplished by "painting" (scanning) a designated area with 

 a radar beam of appropriate characteristics. Two common means for 

 performing this function are shown in Fig. 1-5. 



In the first method, Fig. 1-5A, the picture is "painted" by rotating the 

 antenna beam around an axis perpendicular to the area to be mapped. 

 The resulting picture is a circular map whose center, disregarding trans- 



FiG. 1-5 Radar Mapping: (a) Forward-Look System, Variant of the Plan Position 

 System, (b) Side-Look System. 



lational motion, is the radar's position. The coordinates of the display are 

 conveniently in terms of angle and range. The title "Plan Position" is 

 applied to this type of map. A variant of this scheme would be a system 

 that mapped only a sector of the circle — for example, a sector just for- 

 ward of the radar aircraft (Forward-Look System). 



