Mode selective bandpass filter with high selectivity based on thirty-second-mode circular SIW resonator

In this paper, a thirty-second-mode circular substrate integrated waveguide resonator (TMCSIWR) is firstly investigated, which well retains the fundamental mode and high-order modes (TM0n0 modes) in circular SIW resonator (CSIWR) for stable transmission. Considering miniaturization, high Q and multi frequency selection of TMCSIWR systematically, each TM0n0 mode in TMCSIWR can be effectively selected to achieve independent passband by adjusting feed position and coupling distance. Meanwhile, each TM0n0 mode and non-resonant modes produce multiple transmission zeros by mode coupling. Furthermore, arc groove disturbance effectively adjust coupling to achieve high selectivity. Finally, a multi-zero TM030 mode TMCSIW bandpass filter is designed and fabricated. The measured results are in good agreement with the simulated results.