Dual-mode dual-band microstrip bandpass filter based on stepped impedance resonator (SIR) for wireless communication applications

摘要

In this letter, a dual-mode dual-band microstrip bandpass filter (BPF) based on stepped impedance resonator (SIR) for wireless communication applications is introduced. By choosing a proper impedance ratio, a BPF operating at 2.4/5.2 GHz is designed and analyzed. By adjusting the perturbation size, two degenerate modes are excited and coupled within the first passband. Two transmission zeros which further improve the performance of the BPF locate on both sides of the first passband. The fractional bandwidth (FBW) of the two passbands are 8% and 6%, respectively. The maximum insertion loss (IL) is better than 0.9dB and the return loss is better than -20dB.