H. Kanaya et al., MICROWAVE CHARACTERISTICS OF YBACUO COPLANAR WAVE-GUIDE RESONATORS FABRICATED BY THE SOL-GEL PROCESS ON POLYCRYSTALLINE MGO, JPN J A P 1, 36(10), 1997, pp. 6311-6315
High temperature superconducting (HTS) Y-Ba-Cu-O (YBCO) films were pre
pared on MgO polycrystal substrates by the sol-gel process. The resist
ivity at DC and the surface resistance (R-s) at a microwave frequency
of the films were measured. R-s was found to be highly dependent on th
e thickness of the films and the temperature, and the optimal value ob
tained for R-s was 4.2 m Omega at 40 K and 10 GHz. We also fabricated
a YBCO coplanar waveguide (CPW) half-wavelength resonator around 2 GHz
and compared its RF property with that of a normal metal. The inciden
t power dependence of the transmission characteristics was observed to
examine the power handling capability of the HTS resonator. As the te
mperature and the input power decreased, the quality factor (Q(0)) of
the YBCO CPW resonator improved significantly, as opposed to hardly an
y change of that of a normal metal.