Study of Ionospheric Effects on Azimuth Imaging for Medium-Earth-Orbit Sar

Abstract

The Medium-Earth-Orbit SAR (MEOSAR) is one of the most potential next-generation spaceborne SARs for its excellent performances. However, the MEOSAR may not be able to produce data useful for science applications due to ionospheric effects. So it is very necessary to study ionospheric effects for the development of MEOSAR. In this paper, we present ionospheric effects on azimuth imaging for MEOSAR. First, we established an analysis model for ionospheric effects on azimuth imaging of MEOSAR based on the system characteristics of MEOSAR and the temporal-variability of ionosphere. Then, based on the analysis model, we analyzed the effects caused by the quadratic and cubic phase errors induced by temporal-variability of ionosphere on azimuth imaging. According to the results of our analysis, we conclude that both the quadratic phase error and the cubic phase error neglected for Low-Earth-Orbit SAR (LEOSAR) will deteriorate the azimuth imaging for MEOSAR. Furthermore, ionospheric effects will become more and more serious with the increase of SAR altitude and the improvement of azimuth resolution designed.

Study about the effects on range imaging for MEOSAR induced by ionospheric irregularity

“…Long synthetic aperture time with several or tens of minutes and broad swath with thousands of kilometres are the prominent characteristics for MEOSAR. According to the literature, the variability of the ionosphere will affect SAR imaging not only in range but also in azimuth [12–18].…”

Impacts of Temporal-Spatial Variant Background Ionosphere on Repeat-Track GEO D-InSAR System

“…Therefore, the ionosphere temporal-spatial frozen model is invalid for the analysis of the impacts of background ionosphere variation on D-InSAR processing in a GEO SAR case. In addition, although some researches have applied the temporal-spatial background ionosphere variation model in previous studies, they mainly focus on the analysis of the impacts of the ionosphere on GEO SAR imaging [1,25,26]. Considering the above reasons, impacts of the temporal-spatial variant ionosphere on the deformation retrieval in GEO D-InSAR need to be specially considered.…”