204 



ECHOES AND TARGETS 



lengths, the lobes are so close together that it becomes 

 practically impossible for an aircraft to remain in a 

 null for an appreciable time. 



It was inquired whether drops of more than 3 db 

 were to be expected for other aspects, such as 45 

 degrees. Wliile a complete series of measurements had 

 not yet been made by the author's group, measure- 



ments on three or four aircraft in various aspects had 

 revealed no drops below 2 db. Although the calibration 

 had been carried out entirely with signal generators, 

 standard targets consisting of corner reflectors and 

 spheres had been set up later and produced results in 

 substantial agreement with the theoretically predicted 

 values. 



