Novel bandpass filter with high selectivity and very wide stopband using open stub loaded and DGS

Abstract

A novel bandpass filter (BPF) based on half-wave-length (λ/2) stepped-impedance resonators (SIRs) is proposed in this paper. By properly designing the impedance ratios of the SIRs, the spurious harmonics of the filter can be pushed to upper frequency. With several bandstop structures such as open stubs and defected ground structures (DGSs) applied to the BPF, a good stopband performance is obtained. Moreover, 0° feed structure is used to improve the selectivity of the BPF. Then a BPF which has high selectivity and wide stopband is implemented. Measured results show good agreement with the simulated results.