A COUPLED RESONATOR REFLEX KLYSTRON 



741 



Table I — Determination of Mode Shapes from Complex 

 Admittance Plane Plot of Figure 9(a) 



The results of this analysis are shown in Fig. 9. This illustration, in 

 addition to giving detailed performance characteristics for the 3 + J:^ 

 mode, also indicates clearly the wealth of information which may be 

 obtained from the complex admittance plane representation. Although 

 the curves shown are self-explanatory, a few comments regarding their 

 significance would seem to be in order. It is seen, for instance, that a 

 coupling coefficient so adjusted that (Qkf lies between 0.2 and 0.4 

 will produce a frequency range of essentially constant power. In par- 

 ticular, if we pick the curve for {Qkf = 0.4 from the family of curves 

 of Fig. 9(d), it will be seen that the variation in power over a bandwidth 

 of Q8 = ±0.4 is ±2 per cent, while the corresponding value for the 

 single resonator case, i.e., (Qkf = 0, is minus 23 per cent. As the value 

 of {Qkf is increased beyond 0.4, the depression in the center of the mode 

 becomes increasingly pronounced until it turns into a cusp for (Qk) = 1. 

 Mode shapes for (Qkf > 1, though of no direct interest to this in- 

 vestigation, are indicated in Fig. 10 since they may be encountered in 

 practice in cases of excessively tight coupUng and could then be recog- 

 nized as such. If the mode is traversed in the direction of increasing 

 I Vr I (or increasing frequency), such that the intersection of the electronic 



