Design of a high selectivity dual-band bandpass filter with stepped impedance resonator

A novel dual-band bandpass filter using dual-mode stepped impedance resonator structure (DMSIRs) and traditional stepped impedance resonator structure (SIRs) for dual-band applications at 2.4 and 5.12 GHz is proposed in this paper. By combing the DMSIRs of traditional SIRs, the two passbands are generated with the sum of the mutual coupling between the two structures. Additionally, the cross coupling structure and dual-mode behavior supply the multi-transmission zeros to possess the filter with applicable passband selectivity. The theoretical and measured results are presented and shown with good agreement.