三维LOD-FDTD方法在PMC边界处的精确格式

摘要

证明了局部一维时域有限差分( LOD-FDTD)方法实现理想磁导体( PMC)边界时的待求场分量系数与传统的LOD-FDTD方法系数不同。通过在获得该系数前应用理想导体边界条件，得到对应的修正系数。计算了单个PMC立方体和对称的两个PMC立方体的双站RCS。计算结果表明， PMC边界作为理想导体表面时，传统LOD-FDTD方法计算误差较大，采用修正系数的计算结果与传统FDTD方法计算结果更为吻合；PMC边界作为截断计算空间的对称面，采用修正系数的计算结果与传统LOD-FDTD方法计算结果相同。采用修正系数处理PMC边界无需区分PMC边界是理想磁导体表面还是截断计算空间的对称面，具有统一的表达式，计算理想磁导体表面较传统LOD-FDTD方法误差更小。%The field coefficient on perfect magnetic conductor boundary is proved to be different from that in the conventional locally one-dimensional finite-difference time-domain ( LOD-FDTD) calculation. The correction coefficient is derived by setting PMC boundary condition before the conventional field coefficient is obtained from the implicit equations. Bistatic RCS calculations of a PMC cube and two symmetrical PMC cubes are provided by using correction coefficient method, conventional LOD -FDTD method and FDTD method, respectively. For the surface of perfect conductor, numerical results of correction coefficient meth-od agree better with those of conventional FDTD. For the symmetry plane truncated computing space, nu-merical results of correction coefficient method agree well with those of conventional LOD -FDTD. The theory proposed in this paper is validated. Correction coefficient method has unified expressions and it is found that less calculation errors occur than conventional LOD -FDTD method is used.