星载双基合成孔径雷达（synthetic aperture radar, SAR）系统突破了传统单基SAR在收发同置下的几何束缚,通过空间分置的灵活构型,具备多种先进工作模式,然而双基SAR在斜视情况下的成像会存在频谱扭曲和空变误差加剧的问题,导致成像质量下降。因此,本文基于正侧视下数值计算的单站等效方法,将其扩展到星载双基SAR的斜视构型,利用线性距离徙动校正和二维频域方位向重采样将斜视数据等效为正侧视,并基于双基斜距历程,利用最小二乘拟合获取等效斜视角、等效速度等参数,完成残余距离徙动校正并实现精确聚焦。本文方法解决了基于数值计算的单站等效方法斜视成像问题,并用仿真实验验证了所提出的方法。
Spaceborne bistatic synthetic aperture radar (SAR) systems transcend the geometric limitations of traditional monostatic SAR imposed by co-located transceiver configurations. By leveraging flexible spatially separated configurations, these systems enable a variety of advanced operating modes. However, bistatic SAR imaging under squint geometries suffers from severe spectrum distortion and exacerbated spatial-variant errors, resulting in degraded image quality. To address these challenges, this paper extends the numerical calculation-based Equivalent Monostatic Algorithm (EMA)—originally derived for broadside geometry—to the squint configuration of spaceborne bistatic SAR. Specifically, the proposed method transforms the squint data into an equivalent broadside geometry by utilizing linear Range Cell Migration Correction (RCMC) and two-dimensional frequency-domain azimuth resampling. Subsequently, based on the bistatic slant range history, a least squares fitting method is employed to estimate key parameters, including the equivalent squint angle and equivalent velocity, thereby completing the residual RCMC and realizing precise focusing. This approach effectively resolves the squint imaging limitations associated with the numerical calculation-based EMA. Finally, simulation experiments are conducted to validate the effectiveness of the proposed method.
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