518 



BELL SYSTEM TECHNICAL JOURNAL 



in the microwave field; and in most cases, it turns out that performance is 

 limited by the same transadmittance to capacitance ratios as apply when 

 the source and load impedances are not purely resistive. The terminology 

 of high frequencies will be used but the analysis applies at all frequencies 

 under the conditions stated. 



Consider the over-all single-stage amplifier of Fig. Al-1 consisting of 

 input resonator, tube and output resonator, to be a single transducer 



0' 



Y/////^////////A 



£l 



B + 



INPUT 



3' 



^y/////////////////////y//////. 



I- 



'<^v^^'A'<zw<m^ 



I 1 1 



H C H 



Fig. Al-1. — Microwave triode amplifier. 



whose gain and bandwidth we wish to relate to the geometry and other 

 pertinent characteristics of the circuits, bulb and electrode characteristics. 

 It is instructive to consider the whole transducer to be made up of three 

 transducers in tandem as follows: 



1. The input passive transducer, extending from the externally avail- 

 able input terminals (jierhaps located somewhere in the driving wave 

 guide or coaxial line) up to the internal in[)ut electrodes right at the 

 boundary of the electron stream. Call this transducer T, ; in the 



