Microstrip circuits of thick-film YBCO on zirconia

This paper presents a review of a programme of work in which microstrip circuits using both thick-film YBCO and normal conductors on 3 mol% yttria-stabilised zirconia substrates have been employed to determine such characteristics as: the thermal expansion of zirconia; the dielectric constant of liquid nitrogen; the dielectric constant of zirconia; the effective dielectric constant of the circuit and dispersion; the circuit attenuation and conductor surface resistance; the effect of substrate roughness. In addition various hybrid designs have been investigated; the results of some oscillator and self-oscillating mixer work are also reported here. The work has been carried out at a temperature of 77 K and a common theme has been the use of the microstrip ring resonator as a central component, operating harmonically at frequencies in the range 500 MHz to 12.5 GHz