High-power HTS planar filters with novel back-side coupling

Novel back-side coupling was used to produce high-power high temperature superconducting (HTS) filters. Several 2.88 GHz, 0.7% equal-ripple bandwidth, 2-pole TE/sub 01/ mode filters were fabricated using Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ HTS thin films on 20-mil LaAlO/sub 3/ substrates. The calibrated, measured performance of the filter at 77 K was <0.1 dB in-band insertion loss and 0.2 dB ripple up to 8 W. The uncalibrated measured performance of the filter was unchanged up to 21 W. This represents a significant advance in the power handling of planar HTS filters. These high-power, high-performance, compact HTS filters were designed to be used in transmitters for satellite communications.