二维海面上舰船目标电磁散射及合成孔径雷达成像技术研究

Research on electromagnetic scattering computation and synthetic aperture radar imaging of ship located on two-dimensional ocean surface

研究了二维海面上三维金属目标的电磁散射计算以及合成孔径雷达(SAR)成像技术.基于物理光学法、几何光学法和射线弹跳法计算了海面与目标镜面反射及相互耦合作用;并用等效电流法计算了目标的棱边绕射作用,该方法考虑了阴影效应,同时为了消除人为截断引起的边缘衍射,采用锥形入射波入射.应用蒙特卡罗法生成的Pierson-Moskowitz谱粗糙面模拟实际海洋面,计算海面上立方体及舰船的双站雷达散射截面,通过与数值算法的结果相比较,验证了该算法的正确性.运用该解析法快速获取不同频率、不同角度入射波照射下海面与目标的复合后向散射场数组,结合SAR成像技术,得到海面上立方体以及不同姿态舰船目标的SAR成像结果.该研究成果在实际海洋遥感、海面上军事目标的探测与识别等领域中具有重要的应用价值.

The electromagnetic （EM） scattering computation and the synthetic aperture radar （SAR） imaging of three-dimensional conduc- tor object located on ocean surface are studied. The EM scatterings of object, ocean surface and the interaction between them are computed based on the geometric optic, the physical optic, the shooting and bouncing ray. The method of equivalent current is used to calculate the diffraction by object edges. The shadowing effect is also included, and the tapered incident wave is chosen to reduce the truncation error. The Pierson-Moskowitz random sea surface is generated by using Monte-Carlo method, and numerical results are provided to validate the approach through the computation of radar cross section for cube and ship objects located on ocean surface. The backscattering electric field data of different frequencies and angles are computed quickly by using this approximate method. Combining the backscattering data and SAR images technology, the images of cube and ship located on ocean surface are obtained. The method introduced in this paper has important theoretical significance in realistic ocean remote sensing and detection of military targets located on ocean surface.