Tl2Ba2Ca1Cu2Ox thin films for microstrip filters

High performance narrowband bandpass filters are required in satellite communication systems. Especially HTS filter banks are particularly attractive because of their low insertion loss and sharp filter skirts needed in input multiplexers, Tl2Ba2CaCu2Ox thin films on 2 "-LaAlO3-substrates and 10x10mm(2)-sapphire substrates were prepared using a two step technology. A Tl-free precursor film is prepared by sputtering, The Tl-incorporation is performed by annealing in a Tl2O loaded atmosphere. The best films show surface resistances below 100 mu Omega at 77K and 4GHz. Two-pole bandpass-filters with a center frequency of 4GHz and a bandwidth of 17.5MHz using dual-mode ring resonators have been fabricated from the films on LaAlO3. The measured passband shape achieved with tuning elements Is In good ag specifications of the design, agreement with the specifications of the design.