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Impacts of ionospheric temporal variability on L-band GEO SAR imaging

The integration aperture time of Geosynchronous synthetic aperture radar (GEO SAR) is much longer than that of LEO SAR. Compared with LEO SAR, of which TEC is assumed to be constant, the time-varying ionospheric effects on GEO SAR imaging can't be ignored, and GEO SAR has the advantages of shorter repeat period and wider swath. Due to the wide swath of GEO SAR, it is necessary to take the effects of ionospheric temporal variance at different targets in a large scene into consideration. The letter analyzes the time-varying ionospheric effects on GEO SAR imaging. Finally, the USTEC data is used to analyze the time-varying effects at whole orbit of GEO SAR, and explore whether the effects are consistent at different targets in a large scene. Simulation results show GEO SAR azimuth imaging performance becomes deteriorated and defocused, and the effects are different at different positions in a large scene.