The theoretical implementation aspects of scattered field prediction and angular glint calculation in near-field region are proposed in this work.First of all,a more refined expression of the Green function is develop...The theoretical implementation aspects of scattered field prediction and angular glint calculation in near-field region are proposed in this work.First of all,a more refined expression of the Green function is developed.In this representation,an expansion center is adopted within the neighborhood of the sources.Then a high-frequency electromagnetic scattering evaluation algorithm is formulated,combining the refined physical optics(PO)and equivalent edge current(EEC)algorithm.The modified method not only retains the conciseness and efficiency of the standard code but also can be directly used in the near field(NF)scattering estimation.Afterwards,two basic concepts of the angular glint are briefly introduced and formulated.The proposed procedure makes preparation for the computation of NF linear deviation.Numerical examples demonstrate the accuracy and efficiency of the NF scattering prediction algorithm.The angular glint characteristics in near-field scenarios are also presented and analyzed in the final section.展开更多
尺寸远大于波长的非规则形状物体的三维散射场的精确快速计算是波与物体相互作用领域的基础问题,具有重要科学意义和广泛的应用价值。目前已发展了多种先进的数值计算方法用于处理复杂形状物体的散射问题。电磁计算领域中的多种高频方...尺寸远大于波长的非规则形状物体的三维散射场的精确快速计算是波与物体相互作用领域的基础问题,具有重要科学意义和广泛的应用价值。目前已发展了多种先进的数值计算方法用于处理复杂形状物体的散射问题。电磁计算领域中的多种高频方法和混合算法近年得到了长足发展,这些为解决电大尺寸目标的电磁散射问题提供了有力工具,但对大的介质目标的散射问题目前还没有有效的解决方案。传统的射线模型中,由于缺乏波阵面形状特性,其计算精度和效率受到很大限制。本文介绍的矢量复射线模型(vectorial complex ray model,VCRM)仍用射线描述场,但将波阵面曲率作为射线的内禀属性来描述波的会聚和发散。基于微分几何和相位匹配推导出的波阵面方程给出了入射波、折射波和反射波的波阵面曲率矩阵之间的关系。在此基础上所发展的VCRM可在射线意义下严格计算射线上任意点场的振幅和相位。将VCRM与物理光学相结合,则可进一步解决射线模型中场的焦散问题。该模型所计算的椭球、真实液柱和悬滴的三维精细散射场已经得到了实验验证。可计算的电尺寸参数达到104量级,在个人计算机上所用时间在千秒以内。此外,该模型的一个简单应用澄清了自19世纪以来艾里彩虹理论中的若干问题。本文将对VCRM的发展做一个综述,从实用角度对该模型的概念和算法做简要、清晰的介绍,并以VCRM在光学成像、彩虹研究和椭球、真实液柱及悬滴等超电大目标三维散射为例展示它的使用方法、计算结果,具体阐述VCRM以上所述的优势。VCRM适用任意形状的波与表面光滑非规则形状物体的相互作用,在电磁计算、自由曲面光学、计算机图形学以及流体光学测量等领域有着广阔的应用前景。展开更多
文摘The theoretical implementation aspects of scattered field prediction and angular glint calculation in near-field region are proposed in this work.First of all,a more refined expression of the Green function is developed.In this representation,an expansion center is adopted within the neighborhood of the sources.Then a high-frequency electromagnetic scattering evaluation algorithm is formulated,combining the refined physical optics(PO)and equivalent edge current(EEC)algorithm.The modified method not only retains the conciseness and efficiency of the standard code but also can be directly used in the near field(NF)scattering estimation.Afterwards,two basic concepts of the angular glint are briefly introduced and formulated.The proposed procedure makes preparation for the computation of NF linear deviation.Numerical examples demonstrate the accuracy and efficiency of the NF scattering prediction algorithm.The angular glint characteristics in near-field scenarios are also presented and analyzed in the final section.
文摘尺寸远大于波长的非规则形状物体的三维散射场的精确快速计算是波与物体相互作用领域的基础问题,具有重要科学意义和广泛的应用价值。目前已发展了多种先进的数值计算方法用于处理复杂形状物体的散射问题。电磁计算领域中的多种高频方法和混合算法近年得到了长足发展,这些为解决电大尺寸目标的电磁散射问题提供了有力工具,但对大的介质目标的散射问题目前还没有有效的解决方案。传统的射线模型中,由于缺乏波阵面形状特性,其计算精度和效率受到很大限制。本文介绍的矢量复射线模型(vectorial complex ray model,VCRM)仍用射线描述场,但将波阵面曲率作为射线的内禀属性来描述波的会聚和发散。基于微分几何和相位匹配推导出的波阵面方程给出了入射波、折射波和反射波的波阵面曲率矩阵之间的关系。在此基础上所发展的VCRM可在射线意义下严格计算射线上任意点场的振幅和相位。将VCRM与物理光学相结合,则可进一步解决射线模型中场的焦散问题。该模型所计算的椭球、真实液柱和悬滴的三维精细散射场已经得到了实验验证。可计算的电尺寸参数达到104量级,在个人计算机上所用时间在千秒以内。此外,该模型的一个简单应用澄清了自19世纪以来艾里彩虹理论中的若干问题。本文将对VCRM的发展做一个综述,从实用角度对该模型的概念和算法做简要、清晰的介绍,并以VCRM在光学成像、彩虹研究和椭球、真实液柱及悬滴等超电大目标三维散射为例展示它的使用方法、计算结果,具体阐述VCRM以上所述的优势。VCRM适用任意形状的波与表面光滑非规则形状物体的相互作用,在电磁计算、自由曲面光学、计算机图形学以及流体光学测量等领域有着广阔的应用前景。
