海面与目标复合散射电磁缩比的误差分析及建模方法研究

Scale model simulation and measurement provide an important approach for predicting the radar cross section (RCS) of targets, which have great advantages in terms of both technology and economics. Many domestic and foreign research institutes have established various measurement systems and equipment that can be used to generate sea wave and measure scattering echo of scale sea surface and ship model. At present, the problem of scale model measurement is that some errors will be caused when the complete consistency of the relative parameters for the scaled and prototype sea surface can't be ensured. So, it needs to modify the electromagnetic (EM) scale model of sea surface under ideal conditions. Aiming at these problems, this project is devoted to analyze the error of EM scale model of sea surface and explore the dependency relationships between the errors under different conditions and the related parameters based on the EM scale theory and scattering model of sea surface. Then, the EM scattering scale model under ideal conditions is modified and the composite EM scattering scale model of the ship target on sea surface is established. Finally, this project will further study the characteristics of scattering coefficient, clutter sequences and Doppler spectrum for the scaled and prototype sea surface, and explore the EM scattering coupling mechanism between the sea surface and ship target through the analysis of the composite scattering characteristics. On the basis of this project, an effective theoretical foundation can be provided for the actual scale model measurement of sea surface and the establishment of new method for target detection under sea clutter background.

缩比模型仿真与测量能够为目标雷达散射截面的预估提供一个重要的方法，其在技术和经济方面具有很强的优势，国内外很多研究机构已经建立了各种测量系统和设备可以对海浪进行模拟以及缩比海面与舰船模型进行散射回波的相关测量。目前实际缩比测试时面临的问题是：海面缩比前后相关参数难以保证完全一致时会带来一定的误差，以及如何修正理想条件下的海面电磁缩比模型。针对此类问题，本项目拟以电磁散射缩比理论和海面散射模型为基础，通过分析海面电磁缩比模型的误差，探索不同条件下误差与有关参数的依赖关系，修正理想条件下的海面电磁散射缩比模型，并建立舰船目标与海面的复合电磁散射缩比模型，开展不同条件下缩比前后海面的散射系数、杂波序列、多普勒谱特性以及海面与舰船的电磁散射特性的研究，探索海面与舰船之间的电磁散射耦合机理。通过本项目的研究，可为实际海面缩比测试以及海杂波背景下目标检测新方法的建立提供有效的理论支撑。

海面与目标的缩比模型仿真与测量可以为实验分析或设计提供必要的信息，能够克服外场实测中所需测试场地庞大、目标回波信号较弱且途中易受干扰、难以保证测量精确性等缺点，是目标雷达散射截面预估的一个重要的方法，其在技术和经济方面具有很强的优势。鉴于缩比模型的重要应用价值，本项目基于电磁缩比理论和复合散射模型主要研究了海面与舰船目标的复合散射模型优化、缩比模型建立和缩比误差分析，探索了海面与目标之间耦合散射机理。. 通过本项目的研究，提出了Kd-tree和GO-PO方法相结合的混合模型，提高了GO-PO方法在计算舰船目标散射、海面与舰船目标耦合散射时面元对入射波和反射波可见性判断的效率。研究了在缩比模型中利用淡水替代海水的可行性以及引入的误差，从海水与淡水的介电常数和菲涅尔反射系数对比定量分析可行性，总结得出可以考虑在频率10GHz以上利用淡水替代海水进行缩比模型测量。. 在项目执行过程中，还研究了三维时空相关海杂波的统计建模方法，以及高海况下破碎波对海面RCS和SAR图像的影响，为后续开展海杂波特性和海面目标SAR成像研究奠定基础。本项目的研究可为实际海面目标缩比测试以及海洋环境中舰船目标的检测与识别提供有效的理论支撑。