Design of a 2.5 THz Schottky-Diode Fourth-Harmonic Mixer

A 2.5 THz fourth harmonic mixer using an antiparallel gallium arsenide Schottky diode pair is demonstrated. Full-wave simulation is utilized to model the diode's parasitics, study loop resonance of the antiparallel diode pair and manage the power down-converted at the second harmonic of the local ocillator (LO). Y-factor measurements result in a mixer noise temperature of 55 000 K at 2.5 THz with a conversion loss of 26 dB. Finally, a compact LO system is developed to drive this mixer that only consumes 6.9 W of dc-power, resulting in a CubeSat compatible system with a receiver temperature of 64 000 K.