SOUND WAVE AND MICROWAVE SPACE PATTERNS 



585 



•oiMIIH 



Fig. 29 — A pattern taken with the microphone and loud speaker transposed. The sound 

 source now scans and the pickup microphone is fixed (behind the lens). The phase 

 signal is still employed indicating contours of equal phase "length" between the fixed 

 and scanning transducers. The similarity to Fig. 7 can be observed. / = 9 KC. 



Fig. 30 — A pattern of a carbon telephone transmitter obtained by the transposition method 



of Fig. 29. The phase fronts are those which would be observed if the microphone 



were radiating sound./ = 4 KC (X = 3.4"). 



