Facta Univ. Ser.: Elec. Energ., vol. 16, No. 1, April 2003,
pp. 41-53
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Electromagnetic Field Distribution of a Nearby Lightning Discharge
Inside an Overground Wire Conductive Structure

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Vesna Javor

**Abstract:**
Lightning is a major natural source of electromagnetic (EM) radiation
and the most impressive one, but only from a secure distance. Its most
dangerous effects happen in the case of a direct strike, but it can also
make damages to electronic systems and equipment from the distances of up to
$1.5$km from the direct strike, i.e. in the case of a nearby discharge.
Lightning EM field can be analysed using Fast Fourier Transform (FFT). One
simple approximation [3] for external pulse field is used and parameters are
calculated for the standard pulse function 1.2/50. EM field of a lightning
discharge induces currents along conductive structures and resulting
field can be obtained using program SPAN. Computer package SPAN for
analysis of conductive structures, consisting of linear cylindrical
segments, in external EM field of time harmonic plane wave of
arbitrary direction and frequency, was made by the author [1,2]. Time response
is obtained performing Inverse Fast Fourier Transform (IFFT) to the results
of program SPAN in frequency domain. The results for EM field inside the
structure and in the near field out of some cage structures on the ground in
the case of a nearby lightning discharge are presented in the paper.

**Keywords:**
Lightning discharge, electromagnetic field, pulse function, Fast Fourier
Transform, wire structure.