HYBRID FINITE-ELEMENT SOLUTION OF A QUADRUPOLE GYROMAGNETIC WAVE-GUIDE

Quadrupole bias fields are applied to ferrite-loaded waveguides in the implementation of nonreciprocal microwave quarter-wave plates. Specif ying the tensor values and demagnetising effects for the ferrite in th is type of bias field is difficult owing to the nonuniformity of the f ield and the existence of nonsaturated regions. A two-stage finite ele ment solver is described here which may be used to evaluate the propag ation characteristics of this type of geometry, Propagation constants are presented here for a magnetised square ferrite waveguide. The diff erential phase shift as a function of applied field is found to be lin ear and a backward wave exists over a narrow frequency band for one of the dominant modes.