GAS-DISCnARCE THAN SM IT-RECEIVE SWITCH 97 



where too and co are respectively the resonant angular frequency and the 

 operating angular frequency. 

 This may be rewritten as 



T = ^-^ ^, (28) 



L'«^o w J 



where Tq is the in tune transmission and Ql is the loaded Q, if one assumes 

 that the 5's and Ql remain unchanged for small departures from the resonant 

 wavelength. 



The input impedance of the cavity in terms of the input line impedance 

 is then 



Z = — % . (29) 



|_COo w J 



+ 5o + 52 



The effect of other resonant modes which have been neglected in this 

 analysis may be included by the addition of a term (cti) in equation (29) 

 giving 



Z = ai + 



; 



Wo I 

 w J 



(30) 



"^ ■ + 5„ + 52 



.Wo 



Equation (30) and equation (2) are identical except for terminology. 



APPENDIX B 

 Experimental Determination or "g" Parameters of Windows 



The derived g-parameters which express the electrical size of a window 

 between a resonant cavity and a surge impedance line were defined in Equa- 

 tions 20 and 21 of Appendix A. Numerical values of these parameters may 

 be of some interest, together with their relation to physical dimensions of the 

 windows. The 721 A test cavity was used for an experimental determina- 

 tion of the relation between window width and "g." This cavity is 2^^ 

 inches inside diameter, and is coupled by means of windows to two -^f, diam- 

 eter coaxial Unes. The width of the windows may be adjusted by rotating 

 the coaxial Unes so as partially to close the openings. The insertion loss 

 through the cavity was measured at 3100 mc. by means of a superheterodyne 

 receiver which included a calibrated attenuator in its intermediate frequency 

 section. The windows were carefully maintained geometrically equal. In 

 this case, 



rpll2 



S = 2(1 - P/2) 



