A compact triple-band high-temperature superconducting (HTS) filter with high selectivity based on self-coupled stepped impedance resonator is proposed in this Letter. By folding the two-opened arms of the λ /2 stepped impedance resonator, inter-resonator coupling has been evolved. Due to theoretical analysis of the resonator, the first three resonant frequencies are used to construct three passbands with controllable frequency ratios and bandwidths by changing coupling coefficient, impedance ratios and length ratio. Finally, a triple-band filter example with frequencies centred at 1.72/4.05/7.6 GHz (frequency ratios of 1:2.4:4.4) is designed, fabricated and tested, which has multiple transmission zeros and compact size. Good agreement between the simulated and the measured results validates the design method.

中文翻译：

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使用自耦合步进阻抗谐振器的高选择性紧凑型三频HTS滤波器

本文提出了一种基于自耦合步进阻抗谐振器的高选择性紧凑型三频高温超导（HTS）滤波器。通过折叠两个打开的手臂λ / 2阶跃阻抗谐振器，谐振器间耦合已经发展。由于对谐振器的理论分析，前三个谐振频率用于通过更改耦合系数，阻抗比和长度比来构建具有可控频率比和带宽的三个通带。最后，设计，制造和测试了一个以1.72 / 4.05 / 7.6 GHz为中心的频率（频率比为1：2.4：4.4）的三频滤波器示例，该示例具有多个传输零点和紧凑的尺寸。仿真结果与测量结果之间的良好一致性验证了该设计方法。