基于FDTD方法的电磁场均匀性研究

针对激励源的不同位置以及数量，用三维FDTD（时域有限差分）方法对矩形谐振腔内电磁场分布进行了模拟。本文采用余弦调制的高斯脉冲激励源，考虑了FDTD方法的Courant稳定性条件，以及空间离散间隔所产生的数值色散等情况。研究了不同情况下观察平面电磁场的均值、方差、能量衰减系数随迭代时间的变化，并引入了变异系数（COV）来评价电磁场分布的均匀性。研究表明：在腔体内部能量达到稳定状态后，单平面多馈口对电磁场的均匀性有较好改善作用。

Research of the Uniformity of Electromagnetic Field Based on FDTD Method

The three-dimensional FDTD （Finite Difference Time Domain） method was used to simulate the electromagnetic field distribution of the rectangular resonant cavity by different positions and amount of the excitation source. The cosine modulated Gaussian pulse excitation source was be used, considering the Courant stability condition and numerical dispersion generate by the spatial discretization interval of the FDTD method. The varia- tion of mean, variance, energy attenuation coefficient in different situation of the observation plane was dis- cussed, and the coefficient of variation （COV） was used to evaluate the uniformity of the electromagnetic field. Studies show that the multi-ports for single-plane has a good improvement in uniformity of the electromagnetic field when the internal energy in the cavity reaches a steady state.