Computation of complex resonance frequencies of isolated composite objects

A technique based on the null-field method is presented to investigate the resonance frequencies and the quality factors of isolated composite dielectric/ferrite resonators. A method of identifying the resonant modes is suggested for nonspherical resonators by analyzing the peaks of their scattering sections in the resonance frequency range. Computed resonance frequencies and quality factors for composite resonators, such as double disks, and tubular resonators with ferrite core are compared with published calculations and experiments. These comparisons show that the technique is an effective and flexible one for investigating composite resonators with relatively complicated geometries