Space-borne SAR imaging degradation due to the ionospheric high order dispersive delay

With a view to the growing demands for detecting bio/geophysical information and foliage/ground-obscured targets on a global scale, using the low-frequency space-borne SAR systems is a promising direction. However, these fine application prospects of such systems are easily obstructed by the ionosphere. Thus, understanding the mechanism of how the ionosphere introduces the undesired effects is necessary. In the past, most correlative studies mainly focus on the effects of group delay, phase advance, Faraday rotation, and ionospheric scintillation. In this paper, the effects of background high order dispersive delay on SAR imaging are analysed in detail, which is rarely mentioned in previous studies. At last, numerical simulations and evaluations of constant, linear and quadratic phase errors due to the high order dispersion are obtained and shown.