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BELL SYSTEM TECHNICAL JOURNAL 



The effective area of the triangular trihedral reflector along the symmetric 

 axis id = O, <l) = 0) can be computed from the geometry of Fig. 4. 



A eff = 0.289 ^ (3) 



where C is the length of one side of the aperture such as CB. The eflfective 

 area at other aspect angles can be computed by relating the echo level at the 

 aspect in question with that along the symmetric axis. 





 50 



40 



30 



20 



10 





 50 



40 



-40 -30 -20 -10 



10 20 30 40 -40 -30 -20 

 ANGLE, e, IN DEGREES 



10 20 30 40 50 



Fig. 8— Echo-response patterns of a triangular trihedral reflector. 



It should be pointed out that the eflfective area for trihedral reflections is 

 independent of wavelength where the reflector is large enough so that 

 geometrical optics prevail. If the wavelength is increased, however, the 

 sharp dihedral peaks at the edges of the pattern will be broader. 



In the case of the triangular corner reflector the response levels for aspect 

 angles of 30°, as measured from the symmetric axis, are down by 10 decibels. 

 For many applications a flatter response pattern is desirable. 



