An adjustable multilayer high-temperature superconductor (FITS) bandpass fi
lter has been fabricated. Taped comb-line filters with multilayer structure
s were designed. YBa2Cu3O7-delta (YBCO) thin films deposited on LaAlO3 were
used to construct the packaged multilayer FITS filter. The electrical leng
th of the resonators in the filter was smaller than a quarter-wave length.
The frequency responses of the filter were measured at liquid nitrogen temp
erature 77 K. The insertion loss of the packaged filter was determined to b
e less than 0.5 dB. By mechanically adjusting the multilayer structure, the
center frequencies of the filter changed from 1.78 to 1.92 GHz, and the va
riations of the bandwidth from 60 to 150 MHz were also obtained.