Electromagnetic scattering from the sea surface is of great significance in radar detection, target recognition, ocean remote sensing, etc. By introducing the action spectrum, the modified spatio-temporal variation wave spectrum is used to establish a nonlinear sea surface with currents in this paper. Traditional capillary wave modification facet scattering model (CWMFSM) can only calculate the backscattering from the wind-driven sea surface. By using the new spatio-temporal variation wave spectrum to modify the scattering amplitude of every facet, the new CWMFSM can be used to calculate the nonlinear sea surface scattering with surface currents. Therefore, the model simultaneously considers the modulation of sea surface wind and currents to the radar back echo. The dependence of backscattering coefficient from nonlinear sea surface on the incident angle and the polarization are discussed. The results verify that the nonlinear model is more consistent with the measurement data. This paper also investigates the Doppler spectrum characteristics of the sea with currents. It is found that the effect of wave–current interaction on Doppler spectra is weaker than that of wave–wave interaction. The SAR images of nonlinear sea surfaces are also simulated and different bands, polarizations, and baseline length effects on sea current detection performance of along-track interference SAR are analyzed.

中文翻译：

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带电流的非线性海面微波后向散射分析：多普勒频谱和 SAR 图像

海面电磁散射在雷达探测、目标识别、海洋遥感等领域具有重要意义。本文通过引入作用谱，利用修正的时空变化波谱建立带电流的非线性海面. 传统的毛细波修正面散射模型（CWMFSM）只能计算来自风驱动海面的后向散射。通过使用新的时空变化波谱来修正每个面的散射幅度，新的CWMFSM可用于计算表面流的非线性海面散射。因此，该模型同时考虑了海面风和海流对雷达回波的调制。讨论了非线性海面的后向散射系数对入射角和偏振的依赖性。结果验证了非线性模型与测量数据的一致性。本文还研究了海流的多普勒频谱特征。发现波-电流相互作用对多普勒谱的影响弱于波-波相互作用。还模拟了非线性海面的SAR图像，分析了不同波段、极化和基线长度对沿航迹干涉SAR海流探测性能的影响。本文还研究了海流的多普勒频谱特征。发现波-电流相互作用对多普勒谱的影响弱于波-波相互作用。还模拟了非线性海面的SAR图像，分析了不同波段、极化和基线长度对沿航迹干涉SAR海流检测性能的影响。本文还研究了海流的多普勒频谱特征。发现波-电流相互作用对多普勒谱的影响弱于波-波相互作用。还模拟了非线性海面的SAR图像，分析了不同波段、极化和基线长度对沿航迹干涉SAR海流探测性能的影响。