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BELL SYSTEM TECHNICAL JOURNAL 



minimum value and some maximum value which may approach unity. 

 For example if the ATR is adjusted to have the same gas-discharge power 

 as that in a TR adjusted for a transmission of T, its low-level in-tune input 

 impedance will be 



Z = 



1 - T 



(38) 



Fig. 32 — The ATR low level loss as a function of the magnetron impedance mth an ATR 

 adjusted to an impedance of 8 -|- jO 



Actually since the gas-discharge power is usually not the limiting factor in 

 the design it is possible to adjust the ATR to have an input impedance of 

 8 or 9 (in terms of the line characteristic impedance), corresponding to a 

 TR low-level transmission of the order of 1/2 db {T = 0.89) and yielding 

 an ATR loss of approximately 1/2 db. 



Since the exact value of the impedance of the magnetron branch is not 

 necessarily known it is convenient to show the dependence of the loss factor 

 F for any given ATR on the magnetron impedance by a plot somewhat 



