Dual-Wideband Bandpass Filter Using Short-Circuited Stepped-Impedance Resonators

A compact dual-wideband bandpass filter featuring two controllable passbands is presented and experimentally validated. The proposed filter uses shorted stepped-impedance resonators to achieve dual-wideband bandpass capability and to minimum size. Design curves are given for the filter design. It is found that the frequency ratio of the second to first band has a wide achievable range. An experimental circuit is fabricated and evaluated to validate the design concept. The measurement results correlated well with the simulation results.