Investigation of dual-mode SIW filters with different port positions

In this paper, three dual-mode bandpass substrate integrated waveguide (SIW) filters with different port positions are proposed. To realize a dual-mode bandpass filter on a single-layer substrate, using metallic via-holes as perturbation will be adopted so as to shift the resonant frequency of fundamental mode to higher frequency while another resonant frequency of the first higher mode keeps unchanged. Moreover, the following scenarios are investigated for the sake of designing a compact structure which consists of three isosceles triangle cavities in the next application, two ports on the waist of the triangle, two ports on the base of the triangle and one port on the waist, the other port on the base. Finally, a 4.1% fractional bandwidth filter is fabricated and tested. The measured results agree well with the simulated ones.