Measurement of in-RF and out-RF band saturation of SIS mixer

In this article we answer experimentally the question of how much spurious signal power level (relative to LO power) can be tolerated by an SIS mixer. Spurious signals that are inside and outside of the signal sideband have been considered. It is demonstrated that about −20 dBc of in-RF-band spurious level can be tolerated. For out-of-RF-band spurious, on the other hand, a level of about −15 to −10 dBc can be tolerated depending on the frequency separation between the LO and the spurious signal. Index Terms — Heterodyne detection, saturation, spurious signals, SIS mixer, Local Oscillator, sub millimeter wavelengths