Grain Boundary Josephson Junction Harmonic Mixer Coupled With a Bowtie Loaded Meander Antenna With Zero-Bias Operation

The high-T
_c
superconducting (HTS) bicrystal YBa
₂
Cu
₃
O
_7-δ
(YBCO) zero-bias-operation Josephson junction (JJ) harmonic mixer coupled with a bowtie loaded meander antenna (BLMA) is proposed and studied at 0.21 THz. When the JJ mixer coupled with the BLMA, the maximal harmonic number increases up to 146 with the conversion efficiency of -63.6 dB at the bath temperature around 4.6 K compared to a mixer coupled with a log-periodic antenna (LPA) of only a maximal harmonic number of 46 with the conversion efficiency of -71.6 dB. The mixer coupled with the BLMA has a higher order harmonic mixing with a lower local oscillator (LO) power of 1.26 dBm, which further illustrates its superiority to that coupled with a LPA with the LO power of 5.59 dBm. The experiment verifies the merits of the JJ harmonic mixer operating at zero bias as a promising device in terahertz regions.