Length reduction of evanescent-mode ridge waveguide bandpass filters

Length reduction of evanescent-mode ridge waveguide bandpass filters is investigated. A generalized filter configuration is proposed to reduce the filter length. It is found that the filter length can be reduced by enlarging the height of the evanescent waveguide. It is also found that the cutoff frequency of the fundamental mode of the ridge waveguide has a considerable effect on the filter length.