]-7] THE AIRBORNE RADAR DESIGN PROBLEM 27 



because the design problems and the techniques used to solve them are 

 strongly dependent upon the operating frequency. 



This method of classification is also important to the system designer 

 because the operating frequency determines certain of the radar's reactions 

 to its physical and tactical environment. For example, an atmosphere 

 heavily laden with moisture is more or less opaque in some bands to the 

 highest radar operating frequencies, whereas the transmission of the lower 

 frequencies is little affected. 



In airborne applications, the smaller size of the higher-frequency radar 

 components has favored the use of S, X, and K bands despite their limita- 

 tions with respect to weather and moving target indication, as discussed 

 in Chapters 4 and 6. 



1-7 THE AIRBORNE RADAR DESIGN PROBLEM 



Preceding sections discussed general radar characteristics. The following 

 problem is of paramount importance: How does the radar designer select 

 and employ the right combination of these characteristics to achieve an 

 acceptable performance level in a given weapons system application? 



The design problem may be divided into two basic parts, problem 

 definition and problem solution. 



Problem Definition. The airborne radar design problem is defined by 

 the weapons system application. In such applications, an airborne radar 

 combines with other system elements — human operators and the airborne 

 vehicle and its associated propulsion, navigation, armament, flight control, 

 support, and data processing systems ■ — to form a closely integrated 

 weapons system designed to perform a specific mission. To achieve a 

 given performance level, the weapons system requires certain performance 

 characteristics from the airborne radar. 



The radar designer's first task is to examine the requirements and 

 characteristics of the complete weapons system. From this analysis, the 

 nature of the airborne radar's contributions to overall weapons system 

 performance (mission accomplishment) may be obtained. Typical examples 

 of the parametric relationships developed in such a study are shown in 

 Fig. l-22a. From such curves, the radar requirements for a desired level 

 of mission accomplishment may be obtained. In addition, the sensitivity 

 of mission accomplishment to changes in radar performance is displayed, 

 thereby providing the designer knowledge of the relative importance of 

 each performance characteristic. 



The derivation of such relationships must be relatively uninhibited by 

 known limitations in the radar state of the art. That is to say, the range of 

 values considered for each of the radar's performance capabilities need 



