High T/sub c/ superconducting CPW bandstop filters for radio astronomy front ends [YBa/sub 2/Cu/sub 3/O/sub 7/-LaAlO/sub 3/]

We have designed and tested a superconducting coplanar waveguide (CPW) bandstop filter consisting of 8 coupled line sections at a center frequency of 1.53 GHz. A packaged 94.7% bandwidth low pass Chebychev design yielded a filter with a center frequency of 1.56 GHz, less than 1.2 dB insertion loss in the passband and better than 28 dB rejection at 20 Kelvin. With a skirt selectivity of 1.53(=BW/sub 1 dB//BW/sub -28 dB/) and low insertion loss this filter is an excellent candidate for suppressing contiguous spurious signals in cooled low-noise receiving front ends.