Electromagnetic Field Due to Lightning Striking on Top of a Cone-Shaped Mountain Using the FDTD

This paper presents the calculation of electric and magnetic fields produced by lightning striking over different configurations of nonflat lossy ground. The computation is performed using finite-difference time domain (FDTD) methods in two-dimensional (2-D) with cylindrical coordinate systems and 3-D with Cartesian coordinates. The FDTD method is validated with several previous approximations for lightning electric field computation, such as Uman equations and simulation of lightning striking on the top of a tower. In this study, it is found that lightning striking on the top of a cone-shaped mountain may produce several variations on an electromagnetic field. An enhancement of the perpendicular and parallel to ground electric field components was observed for a cone-shaped configuration only. For configurations that include flat planes, wave reflections due to the transition between the cone-shaped and flat plane were observed.