Architecture and design of the aquarius instrument for RF and thermal stability

In this paper, we present the architecture and design of the aquarius instrument: a spaceborne combination radiometer-scatterometer in L-band, for measuring ocean surface salinity. In order to achieve the unprecedented measurement stability of 0.1 Kelvin for the radiometer, the scatterometer (for correction of the sea surface roughness) is required to have a calibrated stability of 0.1 dB. Active and passive thermal control was utilized as well as RF self calibration. Novel test techniques were also developed to verify the stability requirement was met.