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.