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BELL SYSTEM TECHNICAL JOURNAL 



In (26), Yo is the characteristic admittance of the Une. For a line of given 

 length, this expression gives the input admittance as a function of frequency. 

 When the frequency is c/^(, the line is a quarter wavelength long, and the 



Fig. 21. — Three "strip t>'pe" cavities commonly used in magnetron resonator sj-stems, 

 each resonant at the frequency c/\. Type {a) is essentially a quarter wavelength (X/4) 

 section of uniform transmission line. It should be noted how types (h) and (c) are physi- 

 cally shorter than type (a) by virtue of the greater relative capacitive loading near the 

 open ends. 



input admittance, if the line is lossless, is zero. In other words, the section 

 of Hne resonates at this frequency. In a quarter wavelength resonator of 



^^ The frequenc}- of resonance, / = c/4/', is the fundamental or lowest frequency of an 

 infinite series of resonant frequencies for which the line length is (2g — l)X/4; 



/, = {2q - \)c/U,q= 1,2,3, •••. 

 These frequencies may be specified by considerations of the phase relationships which must 



