Development of a high stability L-band radiometer for ocean salinity measurements

Future sea surface salinity missions will require Lband radiometers to have calibration stabilities of ≤ 0.05 K over 2 days. This research program has focused on determining the optimum radiometer requirements and configuration to achieve this objective. System configuration and component performance have been evaluated with radiometer test beds at both JPL and GSFC. The GSFC testbed uses a cryogenic chamber that allows long-term characterization at radiometric temperatures in the range of 70 120 K. The research has addressed areas including component characterization as a function of temperature, system linearity, optimum noise diode injection calibration and precision temperature control of components.