Atmosphere Effects on Geosynchronous SAR: Theoretical Analysis and Compensation Method

Atmosphere would bring phase error to the SAR signal traversed therein, and further lead to defocusing phenomenon in the SAR imaging results. The effects of atmosphere include background ionosphere, multiple scattering in turbulent ionosphere and troposphere. Due to Geosynchronous SAR (GEO SAR) has an integration time up to the order of a few hundred seconds, thus the atmosphere within the integration time will varies with the integration time, and it should take the effects of the temporal-variation atmosphere on GEO SAR imaging into consideration. Meanwhile, it needs urgently to research the compensation method of the effects of the temporal-variation atmosphere on GEO SAR imaging. In this paper, it has analyzed the impact mechanism of temporal-variation atmosphere on GEO SAR signal, and established the GEO SAR accurate signal model under the influence of the temporal-variation atmosphere. Then, based on this model, it has analyzed the effects of atmosphere on the GEO SAR range and azimuth imaging. Finally, based on the subaperture partition in azimuth and phase error extracting, it has compensated the GEO SAR imaging defocusing phenomenon caused by atmosphere.