A Folded Sir Cross Coupled Wlan Dual-Band Filter

A compact cross-coupled dual-band bandpass filter based on folded Stepped Impedance Resonators (SIRs) with four controllable transmission zeros is proposed in this paper. A pair of stepped impedance tapped lines is utilized to improve the dual band impedance matching, which reduces the insertion loss of the filter; meanwhile the tapped lines are also coupled with non-adjacent resonators to produce transmission zeros to improve skirt characteristics. At the end of this paper, the simulated and measured results are compared with each other, and good agreement is achieved.