Study of lightning electromagnetic field distribution inside and outside the microwave communication building

In the paper, the finite-difference expression is proposed to calculate the distribution of lightning electromagnetic field inside and outside the microwave station. The mathematical model is built and the initial condition and boundary condition are determined. The calculation method of variable step-size and data temporary storage increase by step is presented. It has solved the problem of abrupt change in medium, which is difficult to solve by an analytical method. The distribution and magnitude of the electromagnetic field inside and outside the microwave station are obtained. The calculation result of the electromagnetic field distribution in free space within the range of lightning stroke is close to the result calculated M.A. Uman.