电离层对星载SAR影响的多相位屏仿真方法

利用多相位屏技术对电离层色散、相位闪烁、幅度闪烁等影响的P波段星载SAR(Synthetic Aperture Radar)回波进行了仿真.将电离层建模为只改变信号相位的多个薄屏,信号在屏之间的衍射效应实现电离层的幅度闪烁和相位闪烁.衍射结果由斜入射条件下球面波的抛物方程在自由空间的解析解得到.穿过多相位屏的信号复振幅中包含了电离层色散、相位闪烁、幅度闪烁等影响.回波信号通过发射信号的频谱与受电离层影响的复振幅相乘得到.仿真表明,该方法可以真实反映电离层色散、相位闪烁、幅度闪烁等效应,为研究电离层影响下的星载SAR成像提供真实可靠的数据.

Simulation method of ionospheric effects on spaceborne SAR using multiple phase-screen technic

Spaceborne P band SAR echo affected by the ionosphere was simulated using a multiple phase screen(MPS) method.Ionospheric dispersion effects,phase scintillation and amplitude scintillation were included in the simulated echo.The ionosphere was modeled into several thin screens which only changes phase of the signal.Phase scintillation and amplitude scintillation were realized by diffraction effects in vacuum between phase-screens.Diffraction result was reached by solving a parabolic equation of a sphere wave under an inclined incident condition.Ionospheric dispersion,phase scintillation and amplitude scintillation were included in the signal complex amplitude propagating through the multiple phase-screens.Echo spectrum was simulated by multiplication of the transmitted signal spectrum with the ionospheric effected complex amplitude.Simulation results show that the ionospheric dispersion effect,phase scintillation,amplitude scintillation can be included in the echo by the new method.Veritable and reliable data of ionospheric affected spaceborne SAR can be available for further study.