具有二次谐波抑制的小型高温超导滤波器设计

Design of miniaturized high temperature superconducting filter with 2nd harmonic suppression

采用全波电磁仿真分析方法,设计制作了8阶高温超导带通滤波器。通过在半波长发夹型谐振器的基础上引入分形及插指结构,使得滤波器整体体积较小,同时可有效解决滤波器二倍频处寄生通带问题。最终滤波器的版图大小为22mm×11mm,达到了滤波器小型化的目的。在77K温度下,测得未经调谐的滤波器中心频率为2451.6MHz,通带宽度为108MHz,通带内插入损耗小于0.28dB,回波损耗优于11.74dB,带外抑制大于45dB,二次谐波寄生通带被抑制到三倍频之外。

In this paper, a 8 - pole high temperature superconducting （HTS） filter was designed and manufactured with full -wave field simulation method. Through adding interdigital capacitor and fractal structure based on hair- pin resonator, it was effective to solve these problems of filter＇ s big volume and parasitic passband of double frequency in the filter. At last, the size of the layout was only 22mm × 11 mm, which reached the purpose of miniaturization. Without any tuning, it was tested at 77K that the filter had a bandwidth of 108MHz, its center frequency was 2451.6MHz, the insertion loss was less than 0.28dB, the return loss was more than 11.74dB, the band rejection was better than 45dB, and the parasitic passband of second harmonic was successfully suppressed beyond three times center frequency.