二维高斯随机粗糙面与其上方三维双立方体复合散射的混合算法

基于数值方法(MOM)与基尔霍夫近似(KA)相结合的混合算法计算了二维随机粗糙面与其上方三维双立方体的复合散射特性。首先建立了随机粗糙面与其上方三维双目标的复合模型,将目标划分为MOM区域,粗糙面划分为KA区域,并采用Monte-carlo方法模拟真实粗糙地面。在复合散射场的求解中,首先求出在仅有初始入射场时多目标表面的感应电流;其次,将目标表面感应电流产生的散射场与外部入射场作为KA区域的入射场,求出KA区域表面的感应电流;最后将KA区域的感应电流产生的散射场与外部入射场作为MOM区域的入射场,利用导体目标表面的狄利克莱边界条件求出目标表面电流以及电流系数,并进一步求解出散射场。通过减小了粗糙面各面元的相互耦合及体-面的高阶耦合作用,极大提升了计算速率。在大小尺寸为L_x×L_y=100λ×100λ的粗糙面与棱边长度为l=2λ的立方体目标复合计算中,使用MoM算法产生了747 886个未知量,计算时间为8 821.5s;而使用MOM-KA混合算法产生未知量为26 868个,计算时间为423.8s,仿真结果同时验证了MOM-KA混合算法的准确性。最后,详细讨论了均方根高度、目标间距、高度及立方体尺寸及对复合散射系数的影响。

A Hybrid Method for Scattering from 3 D Double Cubic above a Randomly Gaussian Rough Surface

In this paper, the composite electromagnetic scattering problem of 3D double cubic above a 2D rough surface is analyzed by the hybrid MOM KA method, which combines the moment(MOM) methods and the Kirchhoff approximation (KA). The composite Electromagnetic scattering model of double target above randomly rough surface is constructed, and the target is divided as MOM region while the rough surface is divided as KA region, the current on the rough surface is obtained through the KA approximation, and construct integral equation on the surface of target so as to get the current on target. The scattering field contains the interaction between the target and the sough surface. The efficiency and the convergence of this hybrid algorithm is numerical validated. By comparing the results with the conventional MOM, the validity and high efficiency of this method are verified. Then the scattering coefficients in different rms of rough surface, the different distance, height and size of target are calculated and discuss in detail.