A high-power dual-mode oversized substrate-integrated waveguide (OS-SIW) filter with flexible transmission zero (TZ) and bandwidth

This paper presents a high-power and sharp-skirt-selectivity bandpass filter with flexible transmission zero (TZ) and bandwidth. The proposed filter consists of three cascaded dual-mode resonant cavities and a bandstop resonant structure. The dual-mode resonant cavity is composed of a substrate-integrated waveguide structure and a mushroom metal structure, which can implement a controllable bandwidth and generate a TZ for sharp skirt selectivity. Meanwhile, the middle dual-mode resonant cavity is an oversized waveguide structure to improve power capacity. Moreover, the integrated bandstop resonant structure is used to generate another flexible TZ. The effect of different dimensional mushroom metal structures and bandstop resonant structures are also analyzed in detail. Finally, the proposed structure is fabricated and tested. Simulation results show that the proposed filter has an insertion loss of -1 dB at the passband 8.9-10.7 GHz with two TZs on both sides of the passband. Additionally, the proposed filter can obtain an 11 MW power capacity. Compared with the traditional filters, the proposed filter possesses high-power and sharp skirt selectivity characteristics, and its position of TZ and bandwidth can be properly adjusted.