Quasi-optical millimeter-wave band-pass filters using high-T/sub c/ superconductors

Quasioptical millimeter-wave band-pass filters using YBa/sub 2/Cu/sub 3/O/sub 7/ high-T/sub c/ superconducting films were fabricated on MgO and LaAlO/sub 3/ substrates. Transmitted power through the filter was investigated in the 75 GHz to 110 GHz frequency range at temperatures ranging from 15 to 300 K. At 15 K the measured center frequency and the bandwidth of the superconducting filter were 92 GHz and 0.85 GHz, respectively. Measurements of YBa/sub 2/Cu/sub 3/O/sub 7/ filters were compared with similar filters fabricated using gold. At 15 K and 92 GHz, an improvement of 75% in the quality factor of the superconducting filter was obtained compared with a similar gold filter.<
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