Miniaturized High-Temperature Superconducting Microstrip and Coplanar Waveguide Filters

Two types of miniaturized high-temperature superconducting filters are described in this paper. The first type is developed by using small-sized microstrip spiral resonators, and the second type by coplanar waveguide quarter-wavelength resonators. The filters have significantly reduced size compared with many previous HTS filters. They are designed by employing an electromagnetic simulator in combination with appropriately chosen equivalent circuits. Their measured frequency responses agree well with theoretical predictions, and show low insertion losses in spite of their small sizes. key words: high-temperature superconductor, microstrip spiral resonator, coplanar waveguide, bandpass filter