Influence of mixed finite conductivity on lightning electromagnetic fields under the ground

In this paper, the lightning electromagnetic fields under the mixed finite conductivity ground were calculated using a modified 2-D finite-difference time-domain (FDTD) method. The data of each grid in the entire area were obtained and expressed into groups of pictures efficiently. The spatial characteristic of the peak value of lightning electromagnetic field and its time derivatives under the complex ground is investigated, which are very important for lightening electromagnetic field shielding. And the influence of mixed finite conductivity on peak value of electromagnetic field and its time derivatives were also analyzed. Furthermore, the method employed has been test and compared with the issued experiment data and results from theoretical approach firstly.