Narrow-band 10-pole Y-Ba-Cu-O filter on sapphire substrate

In this paper we present the design procedure of HTS bandpass filters on sapphire substrate. The filter with 0.4% fractional bandwidth in S-band was designed using an effective CAD tool, based on spectral domain approach. The filter is based on hairpin resonators exhibiting unloaded Q up to 43000 at T=77 K. The anisotropy of the dielectric permittivity of sapphire substrate and the YBCO film contribution in the propagating characteristics have been taken into account. Substrate characteristics and YBCO film model parameters were extracted from microstrip and hairpin resonator measurements. These parameters were used in the filter simulation procedure.