Design of W-band Fin-Line Bandpass Filter With Broadband And Low-Insertion Loss Performance

In this paper, a broadband waveguide bandpass filter (BPF) is proposed using E-plane insert fin-line structure. The design principle is detailed. The characteristics of inductive coupling cell is investigated using the equivalent T-type network and $K$ inverter. Moreover, the relationship between the bandwidth and gap width b1 is numerically studied. It is clear that when the gap width is enhanced, both the bandwidth and the selectivity are improved. As demonstration, a wideband BPF with central frequency 94 GHz and bandwidth 11 GHz (FBW 11.7%) is designed, fabricated and measured. The measured results agree well with the simulated ones.