Novel compact single-band and dual-band bandpass filter based on one-third-mode substrate integrated waveguide

In this paper, a novel structure of One-Third-Mode Substrate Integrated Waveguide Resonator (OTMSIWR) is first proposed, which reduces about 65% size. Based on the OTMSIWR, a single-band bandpass filter (BPF) operats at 4.55 GHz is designed. The single-band BPF has a wide and deep upper stopband. Further, a dual-band BPF using high mode technology based on the single-band filter is designed. The fundamental mode (TM101 mode) and high mode (TM201 mode) are utilized to achieve the dual-band response. The center frequencies locate at the 4.2 GHz and 6.15 GHz, respectively. Two transmission zeros (TZs) are achieved in the dual-band BPF by adjusting the positions of the feeds. To further improve the selectivity of the upper stopband of the dual-band BPF, two pairs of Complementary Split-Ring Resonators (CSRRs) are introduced on the surface of the OTMSIWR, which obtain the desired results. Finally, a single-band BPF and a dual-band BPF are fabricated and tested. The measured results agreed well with the simulated ones, which proved that the proposed structure is a good candidate to design filters.