Microwave bandpass filter fabricated on the double-sided YBa2Cu3O7-delta high T-c superconducting thin films.

High-temperature oxide superconducting thin films are well known for their potential applications in microwave devices because of their excellent microwave characteristics of low loss and low dispersion at 77 K. In particular, double-sided YBa2Cu3O7-delta(YBCO) superconducting thin films in which one-side acts as a low loss ground plane will be used for good base materials in the microwave device applications. We prepared the double-sided superconducting thin films on MgO substrates by using pulsed laser deposition Superconducting transition temperatures were measured to be about 86 K. Microstrip bandpass filters were designed using the Chebyshev method. For this filter, the measured stopband attenuation was greater than 40 dB between the input and output terminals with a matching network Insertion loss at the central frequency was less than 1.5 dB, while return loss was better than 10 dB.