This article presents a novel high-temperature superconducting ultra-wideband filter with a 108% fractional bandwidth. A high-order ladder topology circuit is utilized in the proposed filter to ensure a deep out-of-band rejection. Superconducting quasi-lumped elements are applied to reduce the insertion loss brought by the high-order circuit. The proposed filter derives from a low-pass filter (LPF) with a cut-off frequency at 2.7 GHz. Microstrip transformation is adopted in this LPF to achieve a lower stopband at 0.8 GHz. The proposed transformation provides a possibility to separately tune the lower and upper cut-off frequency in a microstrip filter. The measured results demonstrate a good agreement with circuit analysis and EM simulations, and show an excellent performance.

中文翻译：

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基于梯形拓扑电路和微带变换的HTS宽带带通滤波器

本文提出了一种新颖的高温超导超宽带滤波器，其分数带宽为108％。所提出的滤波器中使用了高阶梯形拓扑电路，以确保深度的带外抑制。应用超导准集总元件以减少高阶电路带来的插入损耗。所提出的滤波器源自截止频率为2.7 GHz的低通滤波器（LPF）。该LPF中采用微带转换，以在0.8 GHz处实现较低的阻带。提出的变换提供了在微带滤波器中分别调谐较低和较高截止频率的可能性。测量结果表明与电路分析和EM仿真具有良好的一致性，并具有出色的性能。