High performance narrowband bandpass filters are required in satellite comm
unication 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 10x10m
m(2)-sapphire substrates were prepared using a two step technology. A Tl-fr
ee precursor film is prepared by sputtering, The Tl-incorporation is perfor
med by annealing in a Tl2O loaded atmosphere. The best films show surface r
esistances below 100 mu Omega at 77K and 4GHz. Two-pole bandpass-filters wi
th a center frequency of 4GHz and a bandwidth of 17.5MHz using dual-mode ri
ng resonators have been fabricated from the films on LaAlO3. The measured p
assband shape achieved with tuning elements Is In good ag specifications of
the design, agreement with the specifications of the design.