Elbaraii, L-Band Radiometer System

L-band (1-2 GHz) microwave radiometry is an important remote sensing technique to monitor soil moisture over land surfaces at the global scale. The ESA L-Band SMOS radiometer mission aims at providing as global maps of soil moisture, with accuracy better than 0.04 m³m^-3 every 3 days, with a spatial resolution better than 50 km. To improve the models used and for specifying the accuracy of the aimed global soil moisture data product, ground based radiometer campaigns before launch, during the commissioning phase and during the operative SMOS mission are important. Furthermore, the availability of ground-based L-band data measured simultaneously with the over-flying SMOS satellite are required for calibration and validation purposes. To address these needs three ELBARA II radiometers are being constructed for ESA. They rely on the proven architecture of the ELBARA radiometer with improvements on the user interface, the mechanics, and the microwave electronics. Especially the development of an Active Cold Load (ACL) as cold reference is expected to improve the radiometric accuracy.