High-T/sub c/ superconducting planar filters with improved performance

The results of design and investigation of band-pass filters are presented. The filter is based on a set of double-resonator structures. The main constituent of the filter is the pair of coupled resonators in the form of modified hairpins. The combination of coupling inside the pair and between the pairs provides the desired filter performance. The 12-pole filter (17/spl times/22 mm) manufactured on the double-sided YBCO films on LaAlO/sub 3/ substrate exhibited at T=50 K, 0.3 dB insertion loss, 15 dB return loss in 4% pass band (f/sub 0/=1.7475 GHz) and 60 dB out of band rejection. Another band-pass filter is 12-pole quasielliptic filter based on quasilumped resonators. This filter area is 21/spl times/32 mm (MgO). Filter was designed with 902.5 MHz center frequency, 25 MHz bandwidth and 70 dB out of band rejection.