An Accurate 2-D Attitude Steering Method for GEO SAR Antenna With Zero Doppler Centroid

Due to Earth’s rotation and the elliptical orbit of GEO SAR, the relative velocity between the ground target and the satellite is not perpendicular to the beam center, resulting in the Doppler centroid being nonzero. It not only brings great challenges to imaging but also reduces interference accuracy and ground-moving target indication (GMTI) ability. This letter proposes an accurate 2-D pitch–roll attitude steering method for geosynchronous synthetic aperture radar (GEO SAR) antenna, which can achieve zero Doppler centroid and greatly reduce the maneuvering angle of satellite antenna on the premise of ensuring that the Earth’s surface can be illuminated by the beam. The angle variation is basically less than 0.22°, which is much smaller than other methods. The proposed attitude steering method can realize the real-time irradiation of GEO SAR to the Earth’s surface and can greatly reduce the difficulty of GEO SAR antenna engineering implementation compared with the traditional attitude steering method. The effectiveness of the proposed method is verified by simulation experiments.