Narrowband balanced absorptive bandstop filter integrated with wideband bandpass response

Abstract

A novel narrowband balanced absorptive bandstop filter (BABSF) with wideband bandpass response is proposed, which consists of four coupled-line sections with open-circuited stubs, two half-wavelength transmission lines, and two ground resistors. Excellent differential-mode response with narrowband bandstop response and wideband bandpass property is realised for high frequency selectivity. Good common-mode suppression can be achieved, rejecting the interference noise. For demonstration, a BABSF prototype operating at 2 GHz is designed with good agreement between simulated and measured results.