Evaluation of electromagnetic fields duo to inclined lightning channel on finitely conductive ground

In this study, the channel angle effects on different components of lightning electromagnetic pulse (LEMP) associated with inclined lightning channel in finitely conductive ground are considered. A finite-difference Time-domain (FDTD) method in 3-D Cartesian coordinates is proposed. By rotating the coordinate system of the inclined lightning channel and applying a contour-path technique, LEMP of inclined lightning channel can be derived equivalently from the proposed method with vertical channel. The electromagnetic fields at different observation points due to inclined channel with different ground electrical parameters are calculated and discussed. The results show that the channel inclined affects markedly the horizontal electric field. When the tilt angle changes to be 45°, the horizontal electric field is almost the same order of magnitude as the vertical electric field. The rise time of the magnetic field decreases as the inclined channel becomes larger. We also found that the horizontal field is more obviously affected by the ground electrical parameters.