Measurements of the AMSU-B antenna pattern

Measurements of the antenna patterns for the high frequency component of the Advanced Microwave Sounding Unit (AMSU-B), to fly on the NOAA-KLM polar orbiting satellites, are reported. They were made on the Compact Antenna Test Range at Queen Mary and Westfield College, London, at three frequencies within the AMSU-B receiver's channels, centered at 89, 150, and 183.31 GHz. The main reflector of AMSU-B's antenna is an offset parabola with a 219-mm diameter aperture. This paper describes the measurements that were made and presents the results of an analysis of them for the three AMSU-B flight models. Measurements of beamwidths, main beam efficiencies, and sensitivity to cross-polarization are all reported. These data are then used to compute simulated antenna temperatures for the space and Earth views and recommendations for correcting the space view and Earth view data due to antenna effects are proposed. The implications for the operational radiometric calibration of AMSU-B are also discussed.