Demonstration of a 25% bandwidth 520-680 GHz Schottky receiver front-end for planetary science and remote sensing

Planetary atmospheres are rich in molecular species with spectral rotational and vibrational signatures in the millimeter and submillimeter frequency range. In particular, the 520-680 GHz frequency ranges offers access to a various amount of minor and major constituents of the atmosphere, including water vapour (H2O), carbon monoxide (CO), hydrogen cyanide (HCN), carbon monosulfide (CS) and their isotopes to derive temperature and wind velocities [1] or surface emissivity [2]. Recently, we have developed and manufactured the 560 GHz subharmonic mixer, showing the excellent performances in the 525-625 GHz frequency region with mixer noise temperature of about 870 K, around 30hf/kB [3]. In this paper we present an update and extensive measurement showing that the mixer’s RF bandwidth can be extended up to 25% keeping the excellent performances. Assessment study of the radiometer modelling and Schottky junction parameter deviations will be presented. A best fit of the junction I/V allows to derive the main diode DC parameters retrofitted to analytical models such as [4]. We discuss efforts on implementation of large bandwidth receiver system, including solutions for local power across large bandwidth [5] or in complex systems using simultaneous molecular line observations [6].