Effect of Nearby Buildings on Electromagnetic Fields from Lightning

ABSTRACT

We present a discussion on the effect of nearby buildings on the electric and magnetic fields radiated by lightning. Electric and magnetic fields radiated from distant natural lightning have been measured simultaneously on the roof of a building (the Power Systems Laboratory of the Swiss Federal Institute of Technology, Lausanne, Switzerland) and on the ground at different distances away from it. The results suggest that the measured electric field on the roof of the 9-m tall building is enhanced by a factor of 1.7 to 1.9, whereas the electric fields on the ground experience a significant reduction due to the shadowing effect of the building. Also, it is shown that for a sensor located on the ground, close to a building, the magnetic field component perpendicular to the building can also experience a significant attenuation, presumably due to the effect of the induced currents in the building. The results are supported by numerical simulations, obtained using NEC-4, in which the building is represented using a simple wire-grid model.