Miniaturized Bandpass Filter Based on Capacitor-Loaded Half-Mode Substrate Integrated Waveguide (HMSIW) and Open-Circuit Stubs

A compact, wideband bandpass filter (BPF) based on half-mode substrate integrated waveguide (HMSIW) is proposed in this paper. The characteristics of the HMSIW is firstly investigated. Furthermore, two additional resonant modes and a broad stopband response at the high frequency band can be introduced by loading two open-circuit stubs. Combining HMSIW and two open-circuit stubs, a compact wideband BPF is designed and the numerical investigations are also carried out. Moreover, the bandwidth of proposed BPF can be adjusted by tuning the parameters of S_l and G_l, respectively. The simulated results show that the proposed BPF has wide bandwidth from 0.34 to 0.47 GHz (32.5%), low insert loss 2.24 dB, and return loss better than 10.9 dB in the passband. Besides, two transmission zeros (TZs) have been introduced on the right side of the passband which improve the stopband suppression and the selectivity.