Computer-aided design of dielectric resonator filters in waveguide sections below cutoff

The letter describes the analysis and design of a class of dielectric resonator filters in waveguide sections below cutoff. In these filters evanescent-mode coupling between the resonators can be realized by either an air-filled waveguide section or a dielectric slab-loaded waveguide section. Metallizing the dielectric slab on both sides reduces the length of the coupling section and improves the stopband attenuation significantly. Filter characteristics can be predicted very accurately using a mode-matching technique to calculate the S-matrix of the filter component. This method accounts for the effect of finite metallization thickness and higher-order modes.