HTS FERROELECTRIC DEVICES FOR MICROWAVE APPLICATIONS/

High Temperature Superconducting (HTS, e.g. YBCO) microwave devices ba sed on bulk or thin film ferroelectrics (e.g. Strontium Titanate-STO) are studied theoretically and experimentally. YBCO/STO/YBCO parallel-p late resonators and filters based on bulk single crystal STO are desig ned for electrically tunable high power filters, phase shifters and ot her devices in the frequency band 0.5 - 2.0 GHz of advanced microwave communication systems. Thin film YBCO/STO Inter-digital Capacitors (ID C), Coplanar Waveguides (CPW) phase shifters/delay lines are also desi gned and studied experimentally for low microwave power applications. Modelling problems of these devices and microwave losses in ferroelect rics are also discussed.