Impedance matching of bow-tie antenna for high temperature superconducting YBCO Josephson junction mixer

Some of terahertz detectors such as high temperature superconducting (HTS) YBa 2 Cu 2 Ox (YBCO) Josephson junction mixer are suffering from impedance mismatching problem with antenna where the junction impedance barely reaches several ohms. This paper presents two impedance matching methods based on impedance-wideband bow-tie antennas. First, a quarter of wavelength impedance matching network is proposed to realize the junction impedance matching across the achieved bandwidth of 33 GHz at the center frequency of 130 GHz. Using the second method, the input impedance of bow-tie antenna is changed by loaded with a meander radiator, where the symmetrical radiation over the bandwidth of 11-GHz is achieved on magnesium oxide (MgO) substrate. These two proposed antennas will be applied in a quasi-optical system within a quartz hyperhemisphere lens to enhance the signal coupling efficiency for HTS YBCO Josephson junction mixer.