volume | PIER Journals

Abstract

This paper systematically analyzes the electromagnetic coupling characteristics between microstrip resonators and proposes a novel structure that enables mutual cancellation of electromagnetic coupling, effectively reducing the spacing between resonators. Based on this approach, a 14th-order compact high-temperature superconducting (HTS) microstrip bandpass filter is designed and implemented. By constructing a folded symmetric resonator structure to minimize the total electromagnetic coupling energy, and by optimizing the non-uniform coupling gaps in conjunction with the coupling characteristics, precise control of the coupling paths is achieved, leading to a significantly enhanced compactness. The filter is fabricated using double-sided YBCO HTS thin films and tested at liquid nitrogen temperature (77 K). Both simulation and measurement results show that the filter operates within the 0.96~1.06 GHz frequency band, exhibits an insertion loss below 0.4 dB, an out-of-band rejection better than 78 dB, and a passband edge roll-off rate exceeding 60 dB/MHz, demonstrating excellent performance in terms of low loss, wide bandwidth, and high suppression.

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Mr. Chenhao Xu

Dr. Chenchen Wang

Dr. Yiqiuzi Shen

Prof. Liguo Zhou