The potential use of HTS filters in satellite payloads

The surface resistance values for various thin films (YBaCaCuO, GdBaCuO and TlBaCaCuO) already show significant improvements over conventional conductors on various substrates. Low loss YBCO and TlBaCaCuO thick films on yttria-stabilised zirconia (YSZ) have been reported by Birmingham and Oxford Universities respectively. Thick films have the added advantage that they can coat large area curved surfaces. A method to characterise HTS materials and substrates using a ring resonators has been developed by Portsmouth University, and measurements on TlBaCaCuO rings are being undertaken. A 4-pole extracted pole filter fabricated from GdBaCuO was commissioned from Marconi Research Centre (MRC). It has been characterised for MMS by Portsmouth University over two temperature cycles between 50 K and 90 K. Excellent reproducibility was seen over each temperature cycle with the supplied data from MRC. The design of a 4-pole elliptic filter using TlBaCaCuO on an MgO substrate is discussed. Work on single crystal dielectric resonator filters is ongoing. The significant advantages and disadvantages of DR/HTS technology have been assessed and are discussed