Design of a 4th harmonic Schottky diode mixer for THz frequencies

This paper focuses on the benefits of subharmonic mixers in the sub-mm wavelength range. To demonstrate the possibility to extend the advantages of 2^nd harmonic mixers with respect to local oscillator requirements the paper discusses higher order subharmonic mixers. Simulation results are presented to show the achievable performance and limitations of higher order subharmonical mixing. For an exemplary 4^th harmonic mixer operating at 600 GHz the circuit simulations predict a conversion loss of around 15 dB. Results of 3D-EM field simulations are presented to demonstrate a very compact split-block realization of the mixer circuitry.