RECTANGULAR WAVE-GUIDE DUAL-MODE FILTERS WITHOUT DISCONTINUITIES INSIDE THE RESONATORS

A new configuration of rectangular waveguide dual-mode filters is pres ented where no discontinuity is present inside the cavities. It is bas ed on the idea that coupling between the two diagonal modes in a squar e waveguide resonator can be obtained by deforming the square cross-se ction into a rectangular shape, Hence, no discontinuity is needed to c ouple the two diagonal polarizations. As a consequence, the input/outp ut rectangular waveguide cross-sections are rotated by 45 degrees with respect to those of the resonator. The advantages of this configurati on are related to the fact that all the cross-sections (as well as the coupling apertures) are rectangular and no tuning is needed.