A simplified model for the quantification of electromagnetic field radiated by grounding grid

The objective of this work is the proposition of a simplified model for the quantification of ElectroMagnetic “EM” field radiated by a grounding grid subjected to a current excitation generated by the lightning strike. Our approach is based on the computation by Hertzian dipole concept and modified image theory in frequency domain of the scattered electric and magnetic field in the vicinity of the grid. In order to implement the Hertzian dipole, the approximate transmission line approach for the calculation of current distribution is used. The currents flowing along interconnected conductors of the grounding grid are computed firstly by solving the two-dimensional partial differential equation for the scalar potential via the finite difference technique in the frequency domain, then this procedure is followed by an integration of the related telegrapher´s equation. The corresponding time domain response is then obtained by the aid of Inverse Fourier Transform. The work is validating through the comparison of the results obtained by our approach with those computed via the NEC4 software.