Current Induced by HEMP (High-Altitude Electromagnetic Pulse) on Wire above Ground (Inducerad Stroem pa Oaendlig Ledning oever Mark pa Grund av Hoeghoejds-EMP)

摘要

The authors have derived an expression for the current induced by a high-altitude electromagnetic pulse (EMP) on a thin wire above ground. The assumption of a thin wire is the only approximation made. Calculations based on the expression are then compared to results derived from transmission-line theory. The authors also discuss a few useful approximations. The conclusions regarding the transmission-line theory is that it describes the exact current quite well in most cases. The highest currents corresponds to H polarized pulses and grazing incidence. This is also when the transmission-line theory deviates the most from the correct result. This concerns the magnitude as well as the rise time of the current.