696 fiELI. SYSTEM TECUM CM. JOVRXAL 



iiuenccd l)y the above functional classilication of radar systems, the me- 

 chanical equij)ment design or arrangement is likewise considerably in- 

 fluenced by the area of use of the radar system. As an illustration of this 

 factor, radar systems may be alternatively classified according to the area 

 of operation as follows: 



A. Ground Equipmoit 



The ecjuipment design of a ground radar system must include provisions 

 foi portability, protection against damage in movement over rough terrain, 

 and for operation under extreme weather conditions. 



H. Wival Surface ]'essel Equipnwiil 



Radar equipment employed on surface vessels is subject to extreme at- 

 mospheric corrosive conditions, severe shock from gunfire and, in some 

 cases, partial immersion in sea water. Large naval vessel installations 

 often involve extreme distances between the location of the various com- 

 ])onents of the radar system. 



(". Airbonie Eijuipmoit 



Mechanical equipment features for aircraft use must include provision 

 for operation over rapidly fluctuating conditions of temperature and atmos- 

 pheric pressure. \'ibration conditions coupled with strict weight require- 

 ments result in many additional ])roblems from the equipment designer's 

 standpoint. 



]*'igures 1, 2, and 3 indicate tyi)ical radar equipments employed on the 

 ground, sea, and air, some component designs of which will be reviewed in 

 later sections of this paper. 



1.2 Tl:c !•' unction of the Radar Receiver 



The basic function of a radar receiver is to translate and present the in- 

 formation received at the radar location in a desirable form. This requires 

 that the receiver contain provisions to enable: 



A. Conversion of the received signals, originally of a microwave fre- 

 quency character, to signals in a frequency region more convenient io 

 utilize. 

 li. .Amplification of the extremely low energy signals as received to 



ami)litu(les useful to the observer. 

 (". ("orrclation of all other a\ailal)lc pertinent data with the received 

 microwave signals to allow determination of the complete coor- 

 dinates and other desired characteristics of the target under observa- 

 tion. 



