土壤表面与部分埋藏多目标复合散射的时域有限差分方法

Finite Difference Time Domain Method for Composite Electromagnetic Scattering from Soil Surface and Partly Buried Multiple Targets

采用Dobson半经验模型和电介质复介电常数表示土壤介电常数的实部和虚部,用指数型分布粗糙面和Monte Carlo方法模拟土壤表面,运用时域有限差分方法研究土壤表面与部分埋藏多个矩形截面混凝土柱复合模型的电磁散射.结果表明:复合散射系数随散射角振荡变化;土壤表面高度起伏均方根、土壤含水率、目标介电常数、入射角对复合散射系数影响较大;土壤表面相关长度、目标截面宽度、高度、间距、倾角对复合散射系数影响较小;目标埋藏深度对复合散射系数几乎没有影响.与其他数值计算方法比较,采用时域有限差分方法既可获得较高的准确性,又可减少计算时间和内存占用量.可以用来计算地、海粗糙面与附近任意多目标的复合散射.

Dobson semi-empirical model and dielectric complex permittivity are used to represent real and imaginary parts of soil dielectric constant.Soil surface is simulated with exponential distribution model and Monte Carlo method.Composite electromagnetic scattering from soil surface and partially buried multiple columns with rectangular cross-section is studied with finite difference time domain method.It shows that composite scattering coefficient oscillates with scattering angle.Root mean square of soil surface,soil moisture content,dielectric constant of target and incidence angle have great influence on composite scattering coefficient.Correlation length of soil surface,width,height,distance of target section,and dip angle have weak influence on composite scattering coefficient.Buried depth of target hardly has effect on composite scattering coefficient.Compared with other numerical methods,finite difference time domain method obtains higher accuracy,and reduces calculation time and amount of memory occupying as well.It can be used to calculate complex scattering from rough ground and sea surface with nearby arbitrary multiple targets.