三维随机粗糙面与目标复合电磁散射的FDTD方法

用时域有限差分方法(FDTD)研究三维周期性延拓的随机粗糙面与上方目标复合电磁散射.用周期性延拓消除数值计算中截取有限大小粗糙面产生的边缘效应,讨论一个周期单元粗糙面的边长与其相关长度之间的关系.给出在FDTD方法中向粗糙面加载入射波的方法,建立了粗糙面上单个三维目标的复合散射FDTD计算模型.数值结果给出粗糙面与目标散射的近场分布,应用近远场变换得到全方位散射角的双站散射系数.比较了三维与二维散射模型的区别.结果显示当粗糙面上放置目标时,其后向散射显著增强.

Numerical Simulation of Electromagnetic Scattering from a 3-D Target over a Randomly Rough Surface Using FDTD Method

A numerical finite-difference time-domain(FDTD) approach for electromagnetic scattering from a dielectric target over randomly rough surface is developed in a three dimensional model.The rough surface is truncated in the simulation by using periodic surface extension.One period of rough surface is related to the surface correlation length.Generation of incident waves upon a rough surface is presented.Numerical model of a target on/above a rough surface is designed.Polarized bistatic scattering from the target and rough surface is obtained based on numerical distribution of near fields.A comparison of three-dimensional and conventional two-dimensional models is made.It shows that the back scattering from a rough surface is significantly enhanced due to the target on/above the rough surface.