474 THE BELL SYSTEM TECHXICAL JOURXAL, MARCH 1957 



10- 



o 

 o 



t 

 z 



5 



10' 



z 



10 



10 



-7 



10' 



10' 



10" 



10' 



10 



-2 



10" 



microwave POWER FROM KLYSTRON, Pq [w] 



Fig. 9 — The ratio of the minimum observable susceptibility to the minimum 

 theoretical value versus microwave power for different crystal detection schemes. 

 Full lines correspond to the predicted sensitivitj' and dots indicate experimental 

 values. 



We define the bucking parameter B by the relation 



Px = BP 



RF 



(55) 



Where Prf is the microwave power at the crystal before and Px after 

 the bucking is applied. We further assume that after the bucking is ap- 

 plied the crystals will operate in the square low region. Combining (49), 

 (50), and (52) and neglecting the term GXk which is small in compari- 

 son to the other term we get for the bucking scheme: 



1 1 

 Xmin-obs 



Xmin-th 



AMP 



+ 



f 



(56) 



SBPrp 

 In order to find the optimum bucking parameter, we set 



dB\ 



Xmin-obs 



77 

 Xmin-th ^ 



= which results in 



B = 



MP J 





(57) 



