FABRICATION OF MICROSTRIP TRANSMISSION-LINE BY HIGH-TC SUPERCONDUCTING MATERIALS

High-Tc ceramic (YBCO) superconducting microstrip transmission lines have been fabricated on MgO and SrTiO3 substrates by a sputtering technique as well as a screen printed method. Sputtering conditions for preparation of microstrip lines are described and properties of the sputter-deposited films are discussed. The characteristic impedance of the microstrip line was measured by a digitizing oscilloscope to compare with the specifications. A satisfactory agreement is obtained with theoretical results at both room and low temperatures. In order to investigate the properties of the fabricated microstrip transmission line, the propagation constants, mainly the attenuation and the phase constant, were measured for a sinusoidal wave with the frequencies from 10 MHz to 26.5 GHz, in comparison with those of Al microstrip line fabricated on the MgO substrate. The results show that the attenuation of YBCO transmission line at 4.2K was about the order of 10(-2) dB/cm, a limit of the experimental equipment, for the frequency up to 10 GHz.