Compact Notched Ultra-Wideband Bandpass Filter With Improved Out-of-Band Performance Using Quasi Electromagnetic Bandgap Structure

Abstract—In this paper, a compact notched ultra-wideband (UWB) bandpass filter with improved out-of-band performance using quasi electromagnetic bandgap (EBG) structure is proposed. Firstly, a UWB bandpass filter based on a stepped-impedance stub-loaded resonator (SISLR) is combined with quasi-EBG structures, which suppress the undesired spurious bands to improve the out-of-band performance. In order to eliminate the interference caused by WLAN, a notched band is introduced at 5.2GHz, which is implemented by adding a folded stepped-impedance resonator (SIR) near the stub of the SISLR. At last, the proposed filter is fabricated and measured. Good performances of the UWB filter have been demonstrated both in the simulated and measured results. 1.