Antenna characterization approach for high accuracy of active phased array antennas on Spaceborne SAR systems

In example of measurements performed in space with TerraSAR-X, an approach for an accurate antenna characterization is described. TerraSAR-X was launched in June 2007 and is a highly flexible X-band radar satellite based on an active phased array antenna. Its primary objective is the acquisition of high quality SAR images in a multitude of possible acquisition modes. As this demand is of paramount importance, an accurate characterization of the antenna is a major task, i.e. thousands of different antenna beams being operated have to be determined precisely for compensating the impact of the antenna on SAR data products. Only then, a spaceborne SAR system based on an active phased array antenna can be successfully commissioned. This paper presents the methodology and results derived from different measurements performed for characterizing an active phased array antenna in flight.