Design of dual-mode SIR bandpass filter based on shorting pin for wireless communication applications

Abstract

A new design of microstrip dual mode band-pass-filter (BPF) by using stepped impedance resonator (SIR) based on shorting pin is proposed. The designed structure use two U-shaped tri-sections SIR resonators coupled to each other and a two coupled line feeding ports each of 50 ohm impedance. Shorting pins are used to excite the upper frequency passband in the re   sponse of the filter due to current distribution perturbation at the locations of the shorting pins.  For demonstration, WLAN (5.2-5.7 GHz) and GSM (1.85-1.99 GHz) and Advanced Wireless Services (AWS) (1.71-1.755 GHz). The return losses are -32.469 dB and -26.18 dB respectively at the operating frequencies of the filter.  The results of  insertion losses of the filter is 0.37 and 0.24 dB during the operating bands and more than 25 dB which consider a good out-of- band rejection.