Ionosphere estimation and correction for geosynchronous SAR based on point target deviation between range sub-images

Ionosphere is an important factor in high-resolution spaceborne synthetic aperture radar (SAR) and geosynchronous (GEO) SAR. An approach based on point target deviation between range sub-images is proposed in this paper to estimate and correct the ionosphere. Due to the dispersion effect, the ionosphere causes propagation delay deviation in range subimages with different carrier frequency. This deviation can be used to estimate the total electron content (TEC) along the propagation path, and then the ionospheric effects can be corrected according to the signal model deduced out in this paper. The simulation results show that our approach is valid and robust.