Mode evolution for rotationally symmetric resonant cavities loaded with inhomogeneous dielectric

The finite integration technique (FIT) has been developed for the numerical solution of interior electromagnetic boundary value problems with rotational symmetry. The main advantage of the FIT computer implementation (FITPAK) is its generality, that is, its ability to solve for resonant frequencies, quality factors, and field distributions for a user-defined number of modes in cylindrical cavities with arbitrary distributions of dielectric media. FITPAK has been applied to investigate the relationship between the modes in cylindrical cavities loaded with piecewise-homogeneous dielectrics, such as typically found in dielectric resonators, and the empty cavities modes