106 



BELL SYSTEM TECHNICAL JOURNAL 



Fig. 21 — The directive gain in decibels of a pair of sources with equal amplitudes. (A), 

 the phase delay between the sources is lirt/X; (B), the phase delay between the 

 sources is tt — lirl/X. 



n-3 



0.10 015 



SEPARATION IN WAVELENGTHS 



Fig. 22 — The gain as a function of separation in wavelengths: n is the number of elements. 



