【摘要】 本文给出了高温超导滤波器的一种低温机械调谐方法,通过调谐滤波器的电场来达到优化性能的目的.此方法可以很好的改善滤波器的性能和提高产品的合格率,使基片厚度的不均匀性以及介电常数的误差对高温超导滤波器性能的影响降到最低,从而最大程度地使测试结果和计算机仿真结果相一致.文中以一个4节的高温超导微带滤波器为例,叙述了该方法的实现过程.其带宽为15MHz,中心频率为2.868GHz,带内插损为-0.04dB,反射损耗为-21dB.文中给出了带外抑制,带内特性等的调谐结果.制备完成的超导滤波器在调谐前的性能较设计结果有较大的偏差.主要表现在带内插入损耗、反射损耗特性和带外抑制的偏差.通过调谐,带内特性和带外抑制有明显的改善.带内插入损耗由调谐前的-0.44dB改善到-0.21dB;反射损耗由调谐前低端带边的-8.2dB改善到-14.27dB,但在高频端没有改善;带外抑制由实测的-28dB最大可以改善为-47dB.理论预测该调谐方法会使通带中心频率向低频端移动,我们也观察到了该现象,中心频率向低频端最大偏移了大约3.1MHz.综合各项参数,调谐后,整体性能更接近设计结果.更多还原

【Abstract】 An HTS filter which tuned at cryogenic temperature was presented in this paper. The electromagnetic field was tuned during the tuning. This technique can be used to correct the deviations from substrate thickness, non uniformity of the substrate thickness and the error of the dielectric constant. The purpose of tuning is to optimize the performance and increase the yield of the HTS filter. The fabricated filter’s performance normally was worse than the design result, including the insertion loss, return loss and out-of-band rejection after the fabrication. As in the sample, a 4-pole filter, with the central frequency of 2.868GHz, -0.04dB of S_ 21 , -21dB of S_ 11 and bandwidth of 15MHz was designed and fabricated. In this report, 4-pole filter was tuned at the cryogenic temperature to show the tuning process. It can improved the S21 from -0.44dB to -0.21dB, return loss in the low frequency ends from -8.2dB to -14.27dB, out of band rejection from -28dB to -47dB, respectively. The central frequency also can be shift to a low end about 3.1MHz. As a result, the performance of the tuned filter is closer to the designed result.更多还原