M.I.M.R.: a conical scanning antenna system for a multifrequency imaging microwave radiometer design, measurements and future developments

M.I.M.R. is the acronym of a Multifrequency Imaging Microwave Radiometer i.e. an instrument whose scientific objectives are the monitoring of the Earth surface and its atmosphere. This monitoring is performed at 6 frequencies: 6.8, 10.65, 18.7, 23.6, 36.5 and 89 GHz. Alenia Spazio is responsible, as prime contractor, for the instrument and antenna system design with the related test activities. This paper describes the radiometer antenna system composed by 3 elements : an offset parabolic reflector named “main reflector” illuminated by a cluster of 9 feeds at the frequencies written above, a small offset parabolic reflector named “cold reflector” used for calibration purposes and pointed toward the cold space at 2.70 K, a box filled with absorbing material named “hot load” which simulates the black body behaviour to allow the instrument calibration at 3000 K