任意平面分层介质中正演计算的快速方法

Fast Algorithm for Forward Computation in Media with an Arbitrary Number of Planar Layers

在非均匀介质电磁散射、逆散射等领域中，正该计算速度直接影响着反演计算效率。快速、高精度的正演计算方法有利于反演效率的改善。对于任意平面分层介质情形，传统高效的数值模式匹配法的正演计算效率并不很高。本文通过首先推得每一纵向分层中场量的汉克尔变换表达，再用快速博里叶变换来完成汉克尔交换计算，从而得到更高效的计算方法。它避免了数值本征模式的求解，特别适于处理平面分层介质中纵向分层较多的情形。对于其它非均匀介质中的电磁散射、逆散射问题，本文方法也具有重要的应用价值。

In the electromagnetic scattering, inverse scattering about inhomogeneous media field,the efficiency of inverse computation is crectly effected by the speed of forward computation. Fast,accurate forward calculating algorithm is helpful to improve the inverse efficiency. The forward efficiency of numerical mode matching(NMM)methed, which was efficient traditionally, is not hight for the case of arbitrary planar layer-media. In this paper, a more efficient method is implemented by attaining firstly the representation of Hankel transform for the field component in each vertical layermedia and finishing the calculation of Hankel transform by fast Fourier transform. It avoids requiring numerical eigenmode, is suit to solve the problem in planar layer-media with a few vertical layers.The present method has also a imPOrtant value for application to solve electromagnetic scattering, inverse scattering about inhomogeneous media except planar layer-media.