Mode conversion losses in highly overmoded waveguide cavities
Abstract
A technique to quantify the effects of mode conversion (MC)losses in highly overmoded waveguide cavity resonators using the WKB method is presented. The WKB theory is accurate for weakly irregular waveguide cavities with small amounts of MC and has the advantage that the MC losses in waveguide cavities can be quantified quickly and cheaply. The objective is to compute the amplitude and phase of a resonant mode in the cavity to zeroth order and then use amplitude and phase of the computed zerothorder fields to compute the amplitude of the converted mode. This approach is valid to the extent that the converted modes are not a major perturbation to the resonant mode. The results of the theory are presented in the context of the tradeoffs associated with the design of an 85GHz TE(1,3) phaselocked gyroklystron oscillator experiment. MC losses in the input cavity are a particular problem, and place limits on the amount of usable beam current (and therefore the output power capabilities of the gyroklystron).
 Publication:

IEEE Transactions on Microwave Theory Techniques
 Pub Date:
 October 1990
 DOI:
 10.1109/22.58692
 Bibcode:
 1990ITMTT..38.1503B
 Keywords:

 Cavity Resonators;
 Waveguides;
 WentzelKramerBrillouin Method;
 Electron Beams;
 Energy Dissipation;
 Gyrofrequency;
 Phase Locked Systems;
 Electronics and Electrical Engineering