IMPACT OF FREQUENCY RESPONSE UNCERTAINTIES ON THE ACCURACY OF AOS/C²OMODO RADIOMETER
Marzo 25, 2026ORBITING AND GROUND RFI MITIGATION STRATEGY IN MICAP L-BAND INTERFEROMETRIC RADIOMETER
Marzo 25, 2026P. G. Arpesi1, M. Grilli1, C. Sopranzi1, V. P. Giove1
1OHB Italia
The Copernicus programme is an evolution of the previous Global Monitoring for Environment and Security (GMES) Programme. The Copernicus Imaging Microwave Radiometer Mission, namely CIMR mission, will provide improved monitoring of the Polar Regions in terms of measurement bands, spatial resolution, temporal resolution and geophysical accuracy as well as European operational continuity of L-band and enhanced AMSR type measurement capabilities.
The CIMR mission space segment consists in a conical scan microwave imaging multi-frequency (L, C, X, Ku and Ka) radiometer, with the capability to uniquely observe a wide range of floating sea ice and related ocean parameters, in particular sea ice concentration and sea surface temperature, and to serve operational systems in non-precipitating atmosphere conditions, day and night.
The correct calibration approach is essential for the radiometric instruments. All radiometers require frequent calibration since the characteristics of the receiver chains do not remain stable over time and are affected by temperature drift. At least two calibration references are needed with linear receivers.
Traditionally, the conical scanning radiometers are based on passive calibration: the two reference points are given by an on-board calibration target (OBCT) acting as a blackbody for the hot target and by a calibration mirror for the cold sky view. The proposed approach of calibration for CIMR foresees instead internal calibration targets that are used as references for the in-flight short-term calibration.
The cold reference is based on an Active Cold Load (ACL) built with BJT/FET transistors that achieves a calibration noise temperature (Tcold) below its physical ambient temperature, in the range of 70K-140K depending on the frequency band. The second calibration point (Thot) is generated by a matched load that generates noise at its physical temperature.
This paper reports the design solutions with main technologies selected for CIMR along with the performance results achieved at the current development phase.
