Propagation effects on radiation field pulses generated by cloud lightning flashes

摘要

As the electromagnetic fields propagate over finitely conducting ground, selective attenuation of the high frequencies takes place. As a result. the signatures of broad-band electromagnetic radiation fields generated by lightning flashes change as they; propagate over such ground. In addition to being a function of the electrical parameters of the ground over which the electromagnetic fields propagate, these propagation effects depend on the height of their source above ground level. This makes the propagation effects on radiation fields from cloud flashes differ from those on the radiation fields generated by return strokes in ground flashes. In this paper the propagation effects on radiation field pulses of cloud flashes are illustrated and it is shown that these effects are not as severe as those of return strokes in ground flashes. (C) 2007 Published by Elsevier Ltd.