Miniaturized High-Temperature Superconducting Filter Using D-CRLH Resonators With Dual Narrow Passbands

In this brief, a novel high-temperature superconducting (HTS) bandpass filter (BPF) with dual narrow passbands using dual-mode dual composite right/left-handed (D-CRLH) resonators is designed. The dual-mode resonator is cascaded by two single-mode D-CRLH resonators, where U-shaped microstrip line inductor is inverted to enclose interdigital capacitors, reducing the circuit size and decreasing the coupling between adjacent resonators. The characteristics of proposed resonator are obtained and analyzed by the equivalent circuit model. Finally, a four-pole dual-narrowband BPF operating at 890 / 1742.2 MHz with equal-ripple of 0.0432 dB is presented, fabricated, and measured, good agreement between the measured and simulated results can be achieved.