A new two-dimensional attitude steering method for GEOSAR - Minimizing the Doppler centroid to zero

Due to the elliptical orbital movement of geosynchronous earth orbit synthetic aperture radar (GEOSAR), the Doppler centroid suppressed by the current attitude steering methods remains the significant residual variation, causing the serious coupling between the range and the azimuth. In this paper, a new two-dimensional attitude steering method minimizes most consummately the Doppler centroid to zero in the whole swath for GEOSAR. We firstly describe the GEOSAR movement model in earth fixed coordinate system, and introduce the orbital parameters law based on the interesting region. Furthermore, for GEOSAR, the Doppler properties along the elliptical orbit are mathematical analyzed, and the new method compensate the residual Doppler centroid to theoretically 0Hz considering the instantaneous satellite velocity and the earth rotation. And then, the comparison between the new method and the previous way is furthermore handled. Finally, for the advance method changes the beam pointing of the antenna, the beam irradiation area in the earth surface is provided a detailed analysis in order to verify its effectiveness.