Band-notched ultra-wideband bandpass filter with broad stopband

Abstract

This paper presents a microstrip ultra-wideband (UWB) bandpass filter (BPF) with a wide stopband region from 10.6 to 30.0GHz. The proposed UWB filter consists of two rectangular stub resonators separated by one section of quarter-wavelength-long parallel coupled line that work at the UWB frequency range. In order to avoid the interference from the upstream and downstream band of around 8 GHz used in shortwave satellite communications, a stepped-impedance resonator (SIR) is coupled to the parallel-coupled line which provides a narrow stopband. The fractional bandwidth of 105% is recorded at the center frequency of 6.3 GHz and the insertion loss of 0.3 dB and return loss of 17.0 dB are achieved in the passband.