摘要:
提出了一种时域有限差分(FDTD)计算中色散介质薄层问题处理的新算法.对于厚度小于一个元胞尺度的电小尺寸色散介质薄层问题,采用将元胞内电位移矢量和磁感应强度加权平均的方法,求得薄层所在元胞内修正点处的等效介质参数.然后根据常见色散介质模型,包括Debye模型、Lorenz模型、Drude模型等,介电常数和磁导率可以表示为jω分式多项式的特点,结合频域到时域的转换关系(即用(δ)/(δ)t代替jω)和移位算子方法得到了修正点处的时域本构关系,进而获得时域递推计算式.数值结果表明,该方法具有通用、节省计算时间、节省内存和计算精度良好等优点.
Abstract:
A novel technique for treating electrically thin dispersive layer with the finite difference time domain(FDTD)method is introduced.The proposed model is based on modifying the node update equations to account for the layer,where the electric and magnetic flux densities are locally averaged in the FDTD grid.Then,based on the characteristics that the complex permittivity and complex permeability of three kinds of general dispersive media model,I.e.Debye model,Lorentz model,and Drude model,may be described by rational polynomial fraction in jω,the shift operator method is then applied to obtain the recursive formulation for D and E,B and H available for FDTD computation is obtained.The model is validated with several numerical examples.The computed results illustrate the generality,memory and time step economy and the precision of presented scheme.
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