波束跃度对星载SAR滑聚模式成像影响分析

Impact of antenna beam granularity on sliding spotlight spaceborne SAR image quality

针对星载合成孔径雷达(SAR,Synthetic Aperture Radar)滑动聚束模式方位向天线波束无法实现空间连续运动而引入虚假目标的问题,提出了波束跃度对成像质量影响的定量化分析方法.首先在方位向天线波束控制前提下,构建了星载SAR滑动聚束模式回波信号的数学模型.在此基础上,采用成对回波理论定性与定量化分析了波束跃度对成像质量的影响,尤其给出了天线最小波束跃度与虚假目标幅度和位置的定量映射关系,并讨论了不同波段下,虚假目标对分辨率、峰值旁瓣比、积分旁瓣比以及系统增益的影响,为系统顶层合理论证天线最小波束跃度指标提供了可靠的理论依据.通过计算机仿真实验验证了提出的理论分析方法的正确性.

Antenna beam in sliding spotlight spaceborne synthetic aperture radar( SAR) cannot continuously scan the illuminated scene,leading to paired-echo in SAR images. A method quantitatively analyzing the impact of antenna beam granularity was presented. Firstly,mathematical mode of sliding spotlight spaceborne SAR was proposed based on the azimuth antenna beam granularity. Then,the qualitative and quantitative studies about the impacts of antenna beam granularity on image quality were proposed. And the expression for determining both amplitudes and positions of paired-echo and the minimum beam granularity was illuminated.Moreover,the impacts of paired-echo on azimuth resolution,integrated side lobe ratio( ISLR),peak side lobe ratio( PSLR) and system gain were discussed,at different operation frequencies,e. g. X-band and C-band.Therefore,the analysis provides a theoretical basis for minimum antenna beam granularity design. Finally,computer simulations testify to the validity of theoretical analysis.