Single- and Dual-Band Bandpass Filters Using a Single Perturbed SIW Circular Cavity

In this letter, single- and dual-band bandpass filters using a single perturbed substrate integrated waveguide (SIW) circular cavity are presented. The perturbed TM010, TM110 (a pair of degenerate modes), and TM210 resonant modes of the SIW circular cavity are used to design the proposed filters. The metallic vias are used to perturb the resonant modes. In addition, slot perturbations are introduced to the cavity to independently tune the center frequencies (CFs) of the passbands. Moreover, desired CFs and bandwidths of the passbands can be obtained by adjusting the perturbation elements. The designed filters are fabricated and measured to validate the present approach.