A COUPLED RESONATOR REFLEX KLYSTRON 



757 



0.10 0.20 0.30 0.40 



WIDTH OF COUPLING IRIS IN INCHES 



0.50 



Fig. 19 — Calibration of coupling iris. Variation of coupling coefficient with 

 width of coupling iris. 



independently by the reflected power method. The significance of this 

 experimental agreement is twofold. It serves to prove the correctness 

 of the calibration curves of Figs. 18 and 19 and beyond that may be 

 regarded as verifying much of the theory of the coupled resonator re- 

 flex klystron. 



4.3.3 Comparison of Experimental and Theoretical Mode Shapes. 

 Knowing the primary (operating) Q and the calibration of the sec- 

 ondary resonator, controlled operating conditions were established and 

 the experimental mode shapes shown in the left hand column of Fig. 20 

 obtained. The first three families of curves in this column are the results 

 of point by point measurements in which repeller voltage, taken as the 

 independent variable, was varied by known amounts about its midmode 

 value and the corresponding values of RF power output and frequency 

 were determined by a thermistor-bridge-wattmeter and high-Q wave- 

 meter respectively. The last family of curves in this group, (d), is derived 

 from (c) ; in it power has been normalized with respect to its maximum 

 value within the mode thus permitting the convenient determination of 

 midmode percentage reduction of power and electronic tuning range 

 to any desired power level for various values of (Qk) . 



Additional details of the test conditions which gave rise to the ex- 



