A broadband suspended stripline bandpass filter

A structure of suspended stripline bandpass filter, with the resonators coupled by turns on both sides of the suspended stripline, is presented. Compared to the traditional suspended stripline BPF with end coupling, this type of filter has much wider pass-band, as well as smaller volume. The filter is realized on a substrate material, RT-Duroid 5880, with the thickness of 0.127 mm, less than 0.9 dB insertion loss has been achieved in the pass-band, from 41 to 60 GHz. Basic agreement between test result and simulation result is attained.