LOW-FREQUENCY (5 MHZ) IMPEDANCE MEASUREMENTS OF ISOLATED AND WEAKLY-COUPLED THICK-FILM YBCO MICROSTRIPLINES

Two-point low frequency impedance measurements of microstrip transmiss ion lines, fabricated from high quality, melt textured, thick YBCO +10 wt%Ag films and lower quality, melt textured, thick YBCO +10 wt%Au fi lms on YSZ substrates, have provided intrinsic properties for these gr anular thick films. Weak-coupling between a thick Au doped YBCO line u nder measurement and a very similar parallel coplanar line carrying ei ther high frequency currents or a d.c. current gave rise to unexpected changes in both the resistance and reactance of the microstripline ne ar T(c) . Analysis of the film conducting path in terms of parallel co nductance and susceptance components gives a temperature dependence ve ry similar to the susceptibility curves obtained from bulk YBCO materi al and their observed structure may be interpreted in terms of a granu lar model.