Novel Compact Dual-Band BPF Using Stub-Loaded Shorted Stepped-Impedance Resonators

In this paper, a novel compact dual-band bandpass filter (BPF) is proposed. It consists of a pair of stub-loaded shorted stepped-impedance resonators (SIRs) and a pair of dual-feedline structures (DFSs). It is shown that the dual-band BPF can be designed with individually controllable mid-band frequencies and passband bandwidths by appropriately choosing the geometrical parameters of the proposed filter structure. Moreover, the filter has three adjustable transmission zeros which improve significantly the performance of the filter. The dual-band BPF, operating at 1.96 GHz and 3.5 GHz, is designed and fabricated, and its measured frequency responses agree well with the simulated results.