基于等效参数的三维涂层目标MCFDTD分析

为精确模拟三维有耗薄涂层问题,提出了一种新的基于等效介质参数的共形FDTD(modified con-formal FDTD,MCFDTD)方法。对于包含薄涂层的元胞,将薄涂层和自由空间用等效介质来代替;元胞中电场采样点处的介电系数和电导率的等效值,通过元胞中涂层介质和自由空间所占的长度加权平均得到,而磁场采样点处的磁导系数和导磁率的等效值,则利用涂层介质和自由空间所占的面积加权平均得到。对于弯曲理想导体表面附近元胞,通过采用围线路径积分导出共形FDTD递推式,包含薄涂层的共形网格在递推式中需采用等效介质参数。涂层理想导体球的计算结果与Mie级数解的比较,说明了该方法的正确性和有效性。

Study on MCFDTD for 3-D coated targets by using effective parameters

In order to simulate 3-D thin-coated targets accurately,a novel modified conformal finite-difference time-domain(MCFDTD) method based on effective parameters is presented.The thin coating and free-space in a cell are replaced by an equivalent medium.The effective electrical permittivity and electric conductivity for E-field samples on the cells are calculated by weighted-length of the medium and the free space,the effective magnetic permeability and equivalent magnetic loss for H-field samples are however calculated by weighted-area of the medium and the free space.The MCFDTD formulas are educed by using the contourpath integral,providing the effective medium parameters are adopted in the formulas when the conformal cell includes thin coating.The accuracy and validity of the MCFDTD are shown by comparison of the scattering by a coated perfectly conducting sphere computed by presented method with the Mie series results.