Evaluation of Electric Fields Radiated by Lightning Stepped Leaders on Finitely Conductive Ground

In this study, we investigate the characteristics of the electric fields associated with an inclined stepped-leader channel in the presence of finitely conducting ground. First, a finite-difference time-domain method in 2-D cylindrical coordinates is proposed. Then, the 2-D cylindrical coordinates is rotated through an angle of given value, the inclined stepped-leader channel can be dealt equivalently as a vertical channel. Thus, the conductivity σ and permittivity ε in the Yee cell along the inclined ground surface are dealt with by applying a contour-path technique. Finally, the propagation effects caused by finitely conducting ground and inclination angle of the stepped-leader channels on the features of the electric fields generated by stepped leaders are discussed. The results show that the rise time, the half-width time, and the peak of the electric field change significantly in propagating over finitely conducting ground.