High-<formula><tex>$T_\rm{c}$</tex></formula> Superconducting Fourth-Harmonic Mixer using a Dual-Band Terahertz On-Chip Antenna of High Coupling Efficiency

摘要： This paper presents a dual-band on-chip antenna coupled high-Tc superconducting (HTS) Josephson-junction sub-terahertz (THz) fourth-harmonic mixer. The antenna utilizes a couple of different structured twin-slots to enable the resonant radiations at two frequencies, and integrates a well-designed coplanar waveguide (CPW) network for achieving good radiation coupling and signal isolation characteristics. The electromagnetic (EM) simulations show that coupling efficiencies as high as -4 dB and -3.5 dB are achieved for the 160-GHz and 640-GHz operating frequency bands, respectively. Based on this dual-band antenna, a 640-GHz HTS fourth-harmonic mixer is developed and characterized in a range of operating temperatures. The mixer exhibits a measured conversion gain of around -18 dB at 20 K and -22 dB at 40 K respectively. The achieved intermediate-frequency (IF) bandwidth is larger than 23 GHz. These are the best results reported for HTS harmonic mixers at comparable sub-THz frequency bands to date.