Calculation of return-stroke currents and remote electromagnetic fields using circuit and transmission line theories: Influence of segmentation and excitation function

In this paper, two approaches are used to calculate channel currents in a return-stroke model proposed by the authors. In the first approach, the lightning channel is represented as a transmission line and a Finite-Difference Time-Domain (FDTD)-based technique is used for solving the telegrapher´s equations. In the second approach, the lightning channel is modeled as a cascade of RLC sections using circuit theory. In both cases, the lightning channel is represented as a vertical conductor in the presence of a cloud above a perfectly conducting ground plane. The per-unit-Iength channel parameters are calculated using the charge simulation method. The solution for the currents and remote electromagnetic fields obtained for both models at different positions are compared for different numbers of RLC sections in the modeling using circuit theory, as well as for different voltage excitations at the channel base. The presented results provide a means for evaluating the validity of using circuit theory in the calculation of currents and remote electromagnetic fields generated by lightning.