三维LOD-FDTD方法在PMC边界处的精确格式

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。

Accurate algorithm on PMC boundary for 3D LOD-FDTD method

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 method agree better with those of conventional FDTD. For the symmetry plane truncated computing space, numerical 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.