Ionospheric Effects On GEO SAR Signal

On the basis of the research of ionospheric radio propagation effect, the relatedresearch centered on the effect of ionosphere to the radio system performance of GEOSAR satellite signal propagation and satellite-borne SAR has been studied in thedissertation. According to the analysis of current situation and existing problems, thequantitative analysis of background ionosphere to the satellite-borne SAR signal is clear,yet the major issue and difficult focus on the real-time effect of the core element TEC.Therefore this paper is forced on the effect of background ionosphere and themeasurement of TEC. As the foundation, the medium characteristics in ionosphere andthe basic working principle of GEO SAR are first introduced in the paper. The maintopics and results of the study are as follows:First, the main effects of background ionosphere on the launch and receivingsignals of GEO SAR are phase dispersion and polarization dispersion, and their modelis presented. The effects of background ionosphere to the wave band P, L, and C,including phase beyond, time delay, beam broadening, are showed. We also calculatethe effect of polarization dispersion to the signal envelope.Second, the method which segments the linear modulation signal and thendeduces TEC by differential frequency is given. We have compared the deducing resultand mature methods at present, and also the errors of the two methods.Finally, The model of the effect of ionosphere on the signal resolution of GEOSAR is deduced, and the simulation results of the azimuthal resolution and acrossresolution are also given. We present the method of compensation influence more.