Design of a wideband bandpass filter with dual-mode resonators

In this paper, a wideband bandpass filter (BPF) with dual-mode resonators (DMRs) is proposed and designed by a novel approach. The DMR is equivalent to separate a λ stepped-impedance resonator (SIR) and λ/2 uniform impedance resonator (UIR). The design procedure is step-by-step so as to analysis the circuit structure clearly. Then the dimensions of DMRs can be determined analytically. Moreover, the proposed wideband BPF has the merits of low insertion losses, good return losses and wide stopband. The simulated and measured results are in good agreement.