GAS-DISCHARGE TRANS MIT-RECEIVE SWITCH 



61 



turn coupled to the TR cavity by another window. The input and output 

 windows of the TR cavity are adjusted in size to provide an impedance 

 match to the line during the receiving period. Tlie window to the ATR 

 is, however, adjusted so that it presents a high impedance, that is much 

 greater than the surge impedance, during the receiving period. This high 

 impedance is effectively in series with the magnetron impedance. The 

 resulting high impedance is located at an odd number of quarter wavelengths 

 from the TR and so presents a ver>' low impedance in series with the receiving 

 branch. 



ATR BOX CLAMP 



TR BOX CLAMP 



ATR BOX DISMOUNTED 

 FROM MAIN WAVE 



TR BOX O'SASSEMB-ED 



Fig. 14 — An exploded view of Fig. 13 



Both the TR box and the ATR box must be tuned to resonance at the 

 magnetron frequency. Broad-band ATR boxes using very low Q circuits 

 have been designed which require no adjustment over a 5% band. Such 

 boxes, which obviously are very advantageous in tunable systems, do not 

 use the copper-disc-seal tubes which form the principal subject matter of the 

 present paper, and will not be discussed further. 



TR Box Performance 



The performance of a TR box can be described in terms of four parameters 

 which are related to the four duplexing requirements mentioned earlier. 

 These parameters are respectively: (1) the high level loss, which is the trans- 

 mitting power loss in the TR tube; (2) the leakage power, which is the 

 amount of transmitter power which reaches the receiver; (3) the recovery 

 time, which measures the rate at which the TR box recovers its low level 



