Design and Characterization of 1.8–3.2 THz Schottky-Based Harmonic Mixers

A room-temperature Schottky diode-based WM-86 (WR-0.34) harmonic mixer was developed to build high-resolution spectrometers, and multipixel receivers in the terahertz (THz) region for applications such as radio astronomy, plasma diagnostics, and remote sensing. The mixer consists of a quartz-based local oscillator (LO), intermediate-frequency (IF) circuits, and a GaAs-based beam-lead THz circuit with an integrated diode. Measurements of the harmonic mixer were performed using a 2 THz solid-state source and 2.6906 THz QCL. A conversion loss of 27 dB for the third harmonic mixing and a conversion loss of 30 dB for the fourth harmonic mixing were achieved. This is the first development of a wideband WM-86 (WR-0.34) harmonic mixer with a planar Schottky diode integrated on a beam-lead THz circuit that uses a lower LO harmonic factor for 1.8-3.2 THz RF frequency. Furthermore, this result represents the best Schottky-based mixer in this frequency range.