Power handling capability improvement of HTS filter with sliced microstrip line resonators

Abstract

We investigated the third-order intermodulation distortion (IMD3) properties of high- temperature superconducting (HTS) filters with sliced microstrip line resonators. Electromagnetic simulations indicated that the current concentration along the outer edges of a sliced microstrip line was lower than that of a conventional microstrip line. We fabricated a 3-pole filter with a sliced microstrip line resonator using HTS YBCO thin films and measured the IMD3. Until the input power increase to 7 W, the filter has proper operation from 50 to 77.3 K. The third-order intercept point value of 64 dBm was observed at 70 K. The ΔIMD3 was less than −55 dBc at 1 W input power when the temperature was 50–77.3 K. The sliced microstrip line indicated low ΔIMD3 to the fundamental two-tone sinusoidal waves, which had a difference of 1 MHz, when the input power was 1 W. The results showed that HTS filters with sliced microstrip line resonators have better power handling capability and can feasibly be used in transmitters.