波束跃度对星载方位向扫描模式SAR图像质量的影响

针对星载方位向扫描模式合成孔径雷达(Synthetic Aperture Radar,SAR)系统中天线无法实现连续扫描而引入成对回波的问题,提出了波束跃度对SAR成像质量影响的定量化分析方法。提出了一种广义的SAR成像几何模型,以模式因子区分不同的方位向扫描模式;结合傅里叶级数和泰勒级数展开推导了波束跃度下的方位向天线方向图,在此基础上建立了方位向回波信号模型;得到成对回波幅度和位置与波束跃度的定量关系,着重比较分析了波束跃度对不同方位向扫描模式SAR图像质量的影响。仿真结果验证了上述分析方法的有效性。

Effects of Beam Granularity on the Quality of Spaceborne Azimuth Scanning Mode Synthetic Aperture Radar Images

In terms of the problem of paired echoes in Synthetic Aperture Radar (SAR) images due to that antenna beams in SAR system cannot continuously scan the illuminated scenes, a quantitative analysis method for the effects of antenna beam granularity on the quality of SAR images is presented. First, a generalized SAR imaging model is proposed to distinguish different azimuth scanning modes with the mode factors. Second, based on Fourier series and Taylor series expansion, an antenna pattern formula in azimuth is derived with the azimuth antenna beam granularity, and thus an azimuth echo signal model of spaceborne azimuth scanning mode SAR is established. Finally, the quantitative relationship of the amplitudes and positions of paired-echoes and the antenna beam granularity is achieved, and the effects of beam granularity on the SAR image quality of different azimuth scanning modes are compared and analyzed emphatically. The simulation results verify the validity of the above analysis methods.