Eigenfrequencies in Gyrotropic—Metallic Cavities

In this letter, the eigenfrequencies of a spherical metallic cavity filled with an anisotropic medium are calculated. The loading of the cavity can be gyrotropic (gyroelectric and gyromagnetic), or gyrotropic with the presence of a spherical perfect electric conducting core. We employ a coupled-field surface-volume integral equation (CFSVIE) method, in conjunction with appropriate Dini series expansions for the field quantities, while modified tensorial Green's functions are used to account for the metallic wall of the cavity. This results in the reduction of the CFSVIE to a homogeneous linear system that enables the calculation of the eigenfrequencies. The method is validated by comparison to other independent solutions, and numerical results are given for various kinds of loadings.