Design of an S-band HTS filter with high power capability

A ten-pole S-band high-temperature superconducting filter with excellent frequency response and high power capability is reported in this paper. The filter was fabricated on a 3-in-diameter 0.5-mm-thick LaAlO₃ wafer with double-sided YBCO films. The filter has 4.8% fractional bandwidth centered at 2.15 GHz. The return loss is better than 15 dB, and the out-of-band rejection is better than 80 dB. The power handling capability of the filter was evaluated using a sweep measurement method. The filter has handled 33 dBm (2 W) of input power with no measurable performance degradation over the whole band at 60 K. Furthermore, the in-band (2.11-2.19 GHz) power handling capability of the filter is up to 35.8 dBm (3.8 W) at 60 K.