Waveguide low-pass E-plane cavity and diaphragm filters

A rigorous electrodynamic theory of two types of low-pass filters (LPFs) that are applied in multiband feeders of reflector antennas is presented. The theory comprises a high-efficient method of analysis and numerical multiparameter optimization. Filters of the first type are implemented as rectangular waveguides with E-plane height discontinuities. Filters of the second type employ thin capacitive diaphragms. Fundamental laws of forming the LPF characteristics and a number of optimized versions of these filters are considered.