STUDY ON ATTITUDE CONTROL METHOD FOR ZERO-DOPPLER STEERING IN SPACE BORNE SAR SYSTEM

For the spaceborne synthetic aperture radar (SAR) system, in order to alleviate the complexity of the imaging algorithm and to improve the accuracy of the applications of SAR images, attitude steering is required to reduce the Doppler centroid to 0 Hz. In published literature, twodimensional attitude steering, including yaw and pitch steering, is employed for elliptic orbiting SAR systems. This paper proposes a new steering approach involving only yaw steering to suppress the Doppler centroid of the mid-range to theoretically 0 Hz with a low residual Doppler centroid at the edge of the range extent. This may reduce the complexity of the attitude control system. The comparison of the performances of the current applied methods and the proposed approach is carried out with a simulation, and the effectiveness of the new approach is validated by the results.