Lightning return-stroke transmission line model based on CN Tower lightning data and derivative of Heidler function

The lightning discharge has been studied by many researchers for over a century. One of the most important parameters that is of interest to researchers (especially from the point of view of protection) is the lightning return-stroke current. In order to directly measure the lightning current one must know the exact location of lightning strikes, which can only be accomplished using instrumented tall towers, towers placed on elevated grounds or by rocket-triggered lighting experiments. In most investigations, the lightning current characteristics are determined from measured electric and magnetic fields through the usage of a lightning return-stroke model. In this paper, a lightning return-stroke transmission line (TL) model, based on the measured lightning return-stroke current derivative at the CN Tower is presented. Using the TL model along with the derivative of Heidler function, the paper focuses on the determination of the lightning current special temporal distribution along the current path during the lightning return-stroke phase. Current reflections resulting from the four main CN Tower's structural discontinuities have been thoroughly studied and their proper values are determined and used in modeling of the current distribution along the CN Tower.