时域散射问题中近场－远场转换的新途径

New Approaches to Near－Zone to Far－Zone Field Transformation in Time－Domain Scattering Problems

本文针对散射问题中时域近场一远场转换问题，探讨了两种新的算法．其一是采用Ｓｔｒａｔｔｏｎ－Ｃｈｕ散射场的积分表示式，由表面感应流直接求时域散射远场．其二是采用拉氏变换和卷积的方法，导出求解３－Ｄ和２－Ｄ时域散射远场形式上统一的公式．文中以规则形体为计算实例，验证了算法的可行性．

Focused on the methods of near-zone to far-zone field transformation in solvingscattering problem by FDTD method,two new approaches are presented in this paper. One is directly obtaining scattered far field by adopting Stratton-Chu integral formula. Another method isapplying Laplace transformation and convolution technique which leads to a unified formula forscattered far field in time domain for both 2-D and 3-D scattering problems,and makes 2-D problem a special case of 3-D problem. Numerical results of simple scatterer are given to show the validation of the both algorithms.