CIP法による誘電体円柱の平面波散乱解析

摘要

FDTD method is most popularly used for analysis of electromagnetic wave propagation. However, FDTD tends to show error due to finite difference approximation using electromagnetic field data on discrete grid. Also, special boundary condition to absorb outgoing wave must be set up on the end of analyzing region. Recently, CIP method is paid attention for its accuracy, because it solves hyperbolic advection equation based on data and its derivatives on grid. By applying CIP method to electromagnetic field analysis, improvement on precision would be expected. In this report, electromagnetic wave scattering by a dielectric cylinder situated in free space was demonstrated by analytical approximated method, FDTD method and CIP method. The total field is compared for typical dielectric constants. In evaluation for field intensity by cross-correlation using analytical approximated method as reference, CIP showed better results than FDTD in all case.%現在，電磁波伝搬解析にはFDTD法が広く用いられている．しかし，パルス波の解析において誤差拡散が生じ，また，解析領域の終端に無反射吸収境界条件を考慮する必要がある．そこで，近年CIP法が注目されている．CIP法とは，双曲型の移流方程式を差分法を用いて計算する手法で，離散点における関数値およびその微係数までを用いることから，FDTD法と比較して誤差拡散が少なく，高精度での解析が期待できる．本報告では，2次元電磁界伝搬問題について解析領域に誘電率の異なる円柱を設置した場合をFDTD法，CIP特性曲線法，解析的近似解法で解き，誘電休円柱による散乱波の解析結果を示す．TM波入射の場合の電界強度分布について解析的近似解との相互相関を求めたところ，CIP法はFDTD法より精度が高い結果を示すことが分かった．