A Method of Stopband Widening in BPF Based on Two-Conductor Suspended-Substrate Resonators

Leksikov, Aleksandr A.; Serzhantov, Alexey M.; Govorun, Iliya V.; Afonin, Aleksey O.; Ugryumov, Andrey V.; Leksikov, Andrey A. PROGRESS IN ELECTROMAGNETICS RESEARCH LETTERS, 72 11-16; 10.2528/PIERL17102302 2018

A method aiming to widen the upper stopband in a microwave bandpass filter based on two-conductor suspended-substrate stripline resonators is described in this letter. Applicability of the method is illustrated by simulating and fabricating fourth-order filter that has a very wide upper stopband: Δfstop/f0=7.92 measured at a level -50 dB, which is achieved because the widths of the inner resonators in the structure are 1.4 times greater than that of the outer ones.