Design of Ka band highly selective wideband band-pass filters using directly coupled resonant irises

This paper presents the design of a class of high frequency wideband band-pass filters with high selectivity in waveguide technology. The structure of the band-pass filter is a directly coupled one, i.e., the electromagnetic energy propagates through only one path, so that each resonator is coupled to the previous resonator (or the input) and the following resonator (or the output), without cross couplings between them. The resonators of the filter are resonant irises, while the coupling between resonators is obtained through quarter-wavelength waveguide sections. The paper describes a systematic procedure for the design of such filters using the mode matching method. Results for Ka band satellite communication applications are shown and excellent performances are obtained.