三维介质粗糙面上导体目标散射的解析-数值混合算法

A hybrid analytical-numerical algorithm for computation of scattering from a 3D PEC target above a dielectric rough surface

推导出二维介质粗糙面与其上三维导体目标复合散射的耦合积分方程,提出目标散射的数值矩量法(Method of Moment,MoM)与粗糙面散射的基尔霍夫解析近似法(Kirchhoff Approximation,KA)相结合的混合迭代算法。理论推导表明:当目标距离粗糙面的高度满足条件时,目标的离散单元在粗糙面上任意一点的散射场满足局部平面波关系,利用粗糙面局部面元的反射和透射关系,得出粗糙面感应场的KA解析计算式。由于粗糙表面的感应场用KA解析计算,只需对目标的感应电流进行一次数值积分,无需数值求解粗糙面的积分方程,节省大量的存储空间和运算时间,能在理论上十分简明、数值计算上十分有效地求解三维体目标与面目标组合的复合散射问题。讨论了目标与粗糙面相互作用的互耦迭代算法的有效性和收敛性。结合Monte-Carlo方法产生随机粗糙面样本,数值分析Gauss介质粗糙面上方的规则导体球或任意不规则六面体的散射,讨论了粗糙面的介电参数和目标几何形状等对双站散射的影响。

This paper presents a hybrid analytical-numerical iterative algorithm, which combines the Kirchhoff Approximation （KA） for rough surface and the Method of Moment （MoM） for target, to compute the electromagnetic scattering from a three-dimensiona coupling surface integra （3D） PEC target above a dielectric rough surface. The equations （SIEs） for the composite model are derived based on the Green＇s function of half-space and the Huygens surface equivalence principle. The KA expression for the scattering field of rough surface is derived based on the tangential plane approximation and the right helix relationship. The iteration of KA and MoM takes account the interactions between target and the underlying rough surface. Since is only one numerical integral of induced current on the target performed by KA computation, much memory and computation time is reduced. Convergence and effectivity of the hybrid KA-MoM algorithm is numerically validated, and the effectivity condition is derived. With Monte-Carlo method to generate randomly rough surface samples, an example of bistatic scattering from an irregular hexahedral target above a Gauss rough surface is numerically simulated. Dependences of bistatic scattering pattern upon the surface dielectric property and the target geometry are discussed.