TARGETS FOR MICROWAVE RADAR NAVIGATION 



865 



experiment. The 24-inch reflector was constructed of silver-painted ply- 

 wood and hinged along the intersection of the two upper surfaces so that the 

 angle a could be varied at will. A series of response patterns were taken for 

 various values of a. These are shown in the lower part of Fig. 14. It will 

 be observed that one effect of changmg a is to lower the echo level. This 

 appears, however, to be accompanied by a somewhat flatter response curve. 

 The radar'used in this experiment had a wavelength of 1.25 centimeters. 



WAVELENGTH, \ = 

 1.25 CENTIMETERS 



30 



Z 

 ~ 50 



uj 40 



I 30 



20 



-40 -30 -20 -10 



10 20 30 40 -40 -30 -20 -10 

 ANGLE, e, IN DEGREES 



10 20 30 40 

 Fig. 14— Effect of an error in one of the corner angles of a trihedral ujion its performance. 



A second series of experiments was conducted in which all three internal 

 angles were varied simultaneously. The curves shown in the upper half of 

 Fig. 15 show the axial echo level for various sizes of reflector as a function 

 of the internal angles a. It will be noted that for the 24-mch reflector an 

 angular error of \ degree results in an echo-level reduction of two decibels, 

 while the same angular error in the 9f inch reflector produces only a negli- 

 gible reduction. The lower part of the figure shows some response patterns 



