Study on Precise Satellite Attitude Maneuvering Strategy for Ultrahigh Resolution Spaceborne SAR Imaging

For future ultrahigh resolution spaceborne synthetic aperture radar (SAR), it requires the antenna beam capable of large angle scanning in azimuth to increase the azimuth bandwidth and to improve the resolution consequently. To achieve this goal, this paper proposes for the first time a complete implementation scheme based on three-axis attitude maneuvering of satellite platform. Starting from the determination of rotation center, we will deduce the variation of Euler angles during the whole imaging period. Compared with two-dimensional electronical beam-sweeping approach used in phased-array antenna, the most notable advantage of our approach is that it can guarantee azimuth Doppler frequency barely vary along the range line at any azimuth squint angle, which enables the effective decoupling of the signal in azimuth from that in range. Taking advantage of this characteristic, the processing efficiency of high resolution SAR imaging could then be improved to a great extent. Simulation results are presented to verify its effectiveness as well as superiority compared to electronical beam-sweeping.