Ferrite tunable metal insert filter

A novel type of magnetically tunable waveguide filter is presented which is highly appropriate for E-plane integrated circuit applications. The design theory, which is based on the field expansion into normalised eigenmodes and the modal S-matrix description of the discontinuities, includes both higher-order mode interaction and finite thickness of the E-plane metal, as well as of the lateral ferrite inserts. Optimised design data for two-and three-resonator-type filters are given for midband frequencies of about 15.3-15.4 GHz and 14.1-14.8 GHz. The theory is verified by measurement