Compact E-plane and ridge waveguide filters/diplexers with pseudo-elliptic response

A new class of low-cost and mass-producible filters based on cross-coupled resonators or highly dispersive stubs are introduced. The filters exhibit pseudo-elliptic transfer functions with steep attenuation slopes. They are based on E-plane and ridged waveguide technology and are well suited for millimeter-wave application. Metallic inserts are used not only to determine the filter response but also to separate the folded filter sections and to control the coupling coefficient of the cross-coupled resonators. The designed filters and diplexers are highly compact and much shorter than traditional E-plane filters. At the same time, the ease of manufacturing, known from typical E-plane filters, is preserved.