Evaluation of Electric Fields Radiation by Lightning Return Stroke to Tall Structures at Very CloseDistances Using EM Models and 3D-FDTD Method

In this paper, we present an analysis of the very close electric fields generated by the interaction between lightning and a tall object namely a tower. In this analysis the effect of the buried foundation of this latter on the electric field wave propagation is evaluated. The considered tower is the Peissenberg tower in Germany. Results are carried out using electromagnetic models of lightning current distribution along the tower and along the lightning channel associated to the three dimensions finite difference time domain(3D-FDTD). The latter is combined with the UPML boundary conditions based on the formulation of Taflove. A calculating code is developed on Matlab using the proposed approach. Moreover, in order to validate the developed code, the calculated electric field waveforms are compared with measured data taken from literature. Four different distances, from the bottom of the tower, have been considered (r=15, 30, 60 and 80m) and two configurations have been studied. This is a configuration taking into account the presence of the buried foundation and another not taking it into account. Finally, the obtained results demonstrate that the proposed approach is a good method for evaluate an analyze the lightning electric fields.