MICROWAVE DETECTOR USING GRANULAR-TYPE YBCO SUPERCONDUCTORS

A highly sensitive microwave detector has been developed for the first time by granular-type bulk YBCO superconductors with fine particles. Particles with a size of about 1 µm, having a SNS-like grain boundary, were controlled by a coprecipitation method, followed by a sintering process. A new fabrication method for bulk superconductors was also developed to produce a precise microbridge-type structure. Sensitivity to microwave power below -40 dBm was obtained, and a direct mixing effect was obtained at a frequency of 8.6 GHz at the temperature of 77 K. It was confirmed that the Josephson effect of the detector at the SNS grain boundary formed in the sintering process for ceramics is the most responsive for microwave detection. © 1990 The Japan Society of Applied Physics.