AN ANTENNA THEORY MODEL FOR THE LIGHTNING RETIJRN STROKE

Abstract: A new approach, based on antenna theory, is used to evaluate the lightning return-stroke current as a fitnction of the and height. The lightning channel is modeled as a lossy, straight, attd vertical monopole antentla bove a perfectly conducting round, and is fed by a source voltage. The source voltage is a function of the assumed current at grotmd level and the input impedance of the tnonopole antenna. An electric field integral equation (EFIE) is employed to describe the electromagnetic behavior of the antetma. The mmterical solution of EFIE by the Method of Moments (MOM) in time domain provides the time-space distribution of the current along the lightning channel. This new atttenna-theory model with specified current at the channel base requires only two adjustable parameters: the returtt-stroke propagation speed and the channel resistance per unit length. The new tnodel is compared to the tnost cotnmonly used lightning return-stroke models in terms of the temporal-spatial distribution of channel current and predicted electric fields. 1