利用二维有限差分法对单脊波导TM模进行计算。通过调整网格数目观察计算结果的精度，可以设定出最优的网格数目，然后改变波导中脊的尺寸，观察最低两个TM模对应的截止频率的变化规律，最后给出对应的横截面电场、磁场分布图-The two-dimensional finite difference method to calculate the single-ridge waveguide TM mode. The optimal number of grid can be set by the accur

计算水平点偶极源在地下均匀半空间的电场值-Calculate the horizontal point dipole source in a uniform electric field value of the half-space underground