A 4th harmonic schottky diode mixer - facilitated access to THz frequencies

This paper will present first measurement results of a 4^th harmonic Schottky diode mixer operating at 600 GHz. The mixer design compromises a rectangular waveguide based splitblock with an integrated quartz based mixer circuit. A low parasitic planar antiparallel Schottky diode pair is used to downconvert a 600 GHz signal by mixing with the 4^th harmonic of the local oscillator. The local oscillator for the presented mixer consists of a 150 GHz PLL-locked frequency doubled Gunn oscillator providing a frequency and phase stabilized LO source for accurate measurements of the magnitude and phase of the RF signal. Simulations predict conversion losses well below 20 dB. Current evaluations of the mixer performance are proving the suitability for short range applications like material characterization and testing as well as for life sciences and medical applications.