Electromagnetic field associated with lightning return strokes to a tall structure: influence of channel geometry

The paper is a contribution to the studies of factors that can affect electric (E) and magnetic (H) fields associated with lightning return strokes to tall structure. Herein, the influence of lightning channel inclination upon vertical E-field and azimuthal H-field is analyzed. Input parameters of the simulation (injected current, properties of the tower and of the channel, etc.) are derived from experimental observations. Current distribution is calculated adopting a one-section transmission line model (1TL). For a few characteristic cases of non-vertical channel orientation, E- and H-fields produced at 2 km distance by a lightning strike to the CN tower (546-m height) are computed, and compared to those of the vertical-channel case ("A"). For considered conditions, E-field first peak values differ from the basic case "A" by +9 to -22 %, while at late-time period (within 10 μs) E-values can differ by +152 to -75 %. For H-field, corresponding deviations are smaller: +7 to -16 % and +87 to -61 %.