An Improved Antenna Theory Model of Lightning Return Stroke Using a Distributed Current Source–Part I: Theory and Implementation

An improved antenna theory model (AT) approach in the frequency domain is presented for the electromagnetic analysis of the lightning return stroke channel. The lightning channel is modeled as a wire monopole antenna. Unlike the conventional AT models, which employ a voltage or current source localized at the channel base, the new model considers a distributed current source along the antenna. The implementation of appropriate phase shifts between consecutive current sources in the frequency domain accounts for the current wave propagation speed along the channel. Contrary to conventional AT models, the implemented methodology permits the establishment of an accurate propagation speed along the channel without the necessity to adjust the electrical parameters of the elements representing the channel. A solution of the electric field integral equation by the method of moments in the frequency domain is adopted for modeling the lightning channel and the nearby structures. The presence of multilayer soil is accounted by using Sommerfeld integrals. The implemented methodology enables an efficient analysis of lightning channel in the presence of a complex electromagnetic environment.