采用全波分析法利用二维有限差分法研究了导带宽度对屏蔽带状线两个最低阶TM模的截止频率的影响，计算结果表明，随着导带宽度减小，最低阶TM模截止频率下降，而次低阶TM模截止频率几乎不变。并对有限差分法中网格粗细对计算结果的影响进行了数值实验，发现网格尺寸的选取需在计算精度和数值色散误差之间折中。-With full-wave analysis of the effects of lead shield width stripline two lowest-order TM mode cutoff frequency method using a two-dimensional finite difference method, the results showed that with the reduced width of the guide, the lowest-order TM mode cutoff frequency decreased, while lower order TM mode cutoff frequency is almost constant. Grid finite difference method and the thickness of the impact on the results of numerical experiments and found that the size of the grid need to choose between accuracy and numerical dispersion errors compromise.