FINITE-ELEMENT SOLUTION OF DIELECTRIC-FERRITE RESONATORS

Planar ferrite resonators are widely used in microwave and millimeter- wave junction circulators. Recent trends toward broadbanding and minia turization of devices have led to interest in novel inhomogeneous stru ctures. To simplify design procedures, a finite element package for th e calculation of modal resonant frequencies in terms of a specified ap plied bias field and material magnetization has been developed. The fr equency dependence of the ferrite tensor components is included in the analysis, and so the resulting eigenvalue problem is nonlinear. An it erative finite element scheme is used to solve this problem for resona tors with arbitrary geometries, making full use of the symmetry of the modes. For the special case of homogeneous resonators of arbitrary sh ape the calculations may be simplified through the use of normalized p arameters. To illustrate the technique and the limitations of the use of normalized parameters, a homogeneous ferrite ring resonator and an inhomogeneous dielectric-ferrite ring resonator have been analyzed. In both cases, good agreement with the exact solution is obtained. Calcu lations are also presented for a practical circulator geometry with th reefold symmetry: a dielectric triangle inserted within a ferrite disk .