EMC effects of the lightning protection system: shielding properties of the roof-grid

A suitable set of parameters is used to evaluate the shielding performance of the roof-grid constituted by a mesh of conductors, electrically interconnected, laying on top of buildings with a large-area roof. The influence of the roof-grid on the electromagnetic field inside the building due to a direct lightning strike is shown. The values of the electromotive force induced in loops set at the most significant positions within the structure are calculated for six possible roof-grid configurations. The values of attenuation as a function of frequency and the geometric arrangement of the grid are also indicated. The presence of reinforced concrete walls is not directly taken into account.<>