A high isolation dual-band bandpass filter based on hybrid microstrip/split-loop slot resonator

A novel dual-band bandpass filter (BPF) with high isolation between the two passbands and good selectivity is proposed in this article, which is based on hybrid-coupled microstrip open-circuited stub/split-loop slot multi-bandgap resonator. Based on full-wave electromagnetic (EM) analysis, the proposed filter is found to have the advantage that the both passband central frequencies can be flexibly controlled by the geometric dimensions of multi-bandgap resonator, while the pass-band bandwidths are mainly determined by the cascaded number of the hybrid microstrip/slot resonators. Theoretical prediction is verified by the experimental result of the proposed dual-band BPF.