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BELL SYSTEM TECHNICAL JOURNAL 



phased for one ; Branch B for the other. Again taking x = V2, the im- 

 provement referred to e,/e„ is 10 log iV + 3 decibels. Here eje^ 

 denotes the signal-to-noise ratio in each antenna due to one wave" 

 Referring the improvement to the signal-to-noise ratio of one antenna 



ANTENNA I 



ANTENNA 2 



ANTENNA 3 



®SA ©SB 6c 



©SA ©SB 6a 



I — wv ' 



Ra 



©SA ©SB ©a 



I VW ' 



Ra 



©SA esB ©a 



H.F DETECTORS 



I PHASE 

 r~n SHIFTERS 



r L_. 



ANTENNA N 



^^^ — 7^ — ;=u 



I ID N \ - I N | - 



REC A |REC B 



Es.Ec 



EsB 

 Eqb 



-^ 



EoAo/N'ea'j 



EaB = ^eaU^-/N-|^ 



CASE m. 



SINGLE WAVE A (656= O) 

 BRANCHES A AND B PHASED 

 FOR WAVE A. DELAY ZERO. 

 S/n IN EACH ANT. = esA/ea 



SINGLE WAVE A (Csb^ o) 

 BRANCH A PHASED FOR WAVE A 

 BRANCH B PHASED AGAINST 

 WAVE A. s/n in EACH ANTENNA 



TWO EQUAL WAVES A AND B 

 (©SA=esB = es) BRANCH A 



PHASED FOR WAVE A. BRANCH 

 B PHASED FOR WAVE B. Eja 

 AND EjB DELAY EQUALIZED, s/n 

 IN EACH ANT. = v/2 65/60 



Fig. 34— Simple signal-to-noise analysis of the MUSA system. 



receiving both waves, assumed to add randomly, increases the reference 

 by three decibels and reduces the improvement to 10 log TV decibels. 



This analysis may be expanded to include K waves in which case K 

 branches would be required to obtain the gain of 10 log N decibels re- 

 ferred to one unit antenna. 



