MEO-SAR in-orbit Elevation Antenna Pattern Determination Using Nano Calibration Satellite

Medium-Earth-Orbit synthetic aperture radar (MEO-SAR) is a spaceborne SAR running at orbit altitudes above Low-Earth-Orbit SAR (LEO-SAR) around 2000 km and below the geosynchronous orbit SAR (GEO-SAR) near 35786 km. The MEO-SAR is used to cover wide swaths, which is 4-5 times larger than LEO-SAR. Therefore, the current method based on tropical rain forest (ground-based method) can hardly meet the requirement of wide swath to determine the MEO-SAR antenna elevation pattern. In this paper, a new approach based on a low-cost Nano calibration satellite mounted with a receiver (space-based method) is proposed. Through appropriate orbit elements selection strategy, the Nano calibration satellite can fly across the entire SAR swath, and the receiver that mounted on the Nano calibration satellite will record the MEO-SAR elevation antenna pattern in the same time. Simulation work is performed with STK software, which verifies the feasibility of the proposed space-based method and the increased frequency of antenna pattern in-orbit determination compared to the ground-based method.