Band-notched UWB bandpass filter design using tri-section SIR

A UWB BPF with a 5-GHz notched band and an improved upper stopband has been proposed and designed. By properly locating the first five resonant modes of the TSSIR, we have successfully implemented a five-transmission-pole UWB BPF. The notched band was created by the embedded lambda/4 open stubs. The upper stopband rejection has been effectively enhanced by locating around the first spurious resonant frequency of the TSSIR the transmission zeros produce d by the interdigital parallel-coupled lines and the embedded lambda/4 open-circuited stubs. A prototype of the proposed UWB BPF has been fabricated and measured for performance verification. The simulated and measured results are in reasonable agreement with each other.