The effect of a group of buildings on the lightning electromagnetic fields

Among the various factors that influence the lightning electromagnetic fields, the presence of obstacles such as buildings has deserved some few studies. The paper presents the results related to the influence of a group of buildings on the vertical electric field, by a 3D FDTD code developed for a more complete study. Two rows of concrete buildings were considered, with different heights, areas and separation distances. The fields were calculated at various points on three distribution lines supposed to exist in front of the group of buildings, in its middle and behind it. Two different striking points were considered on the top of two chosen buildings. The simulations have shown a general field reduction due to the group of buildings, depending on their dimensions and heights, and on the position of the lightning striking point, but with not significant dependence on the separation distance between buildings. As expected, in some conditions polarity inversion of the vertical electric field can occur.