Superconducting planar log-periodic antenna for millimeter/terahertz wave receiver

Superconducting Josephson junction (JJ) has potential application in terahertz band. The JJ has ultra low noise temperature and high sensitivity and could directly detect the millimeter and terahertz (THz) waves in the space. The JJ is regarded as an outstanding frequency-voltage converter based on the Josephson relation, f=V/Φ₀, where V is the voltage across the JJ, Φ₀ is the flux quantum and f is the frequency. In this paper, we designed JJs with superconducting planar log-periodic antennas (PLAs) operating at millimeter and THz wavelengths. For the millimeter PLA, we did both of the experiment with high temperature superconducting bicrystal JJ and numerical simulation using electromagnetic software, which showed good consistency. For the THz PLA, we numerically studied its scatter parameter in 0.1-1.1 THz and analysed it at 220 GHz in detail. Moreover, we adhered the PLA to a semispherical silicon lens to strength the coupling between the JJ and the THz wave.