A New Class of Dual-Mode Dual-Band Waveguide Filters

This paper presents a new class of dual-mode dual-band filters in which each polarization is dedicated to a selected band. The equivalent circuit is a parallel combination of two inline networks that represent each polarization. A transmission zero is generated between the two bands by properly adjusting the relative orientations of the input and output coupling apertures. For filters where each branch contains an odd number of resonators, the input and output apertures have the same orientations. For filters where the order of each branch is even, the two apertures are orthogonal to each other. Filters using three and four dual-mode cavities are designed and presented. Different arrangements of the dual-mode cavities are also presented.