Resumen
For different values of the decay constant in the Modified Transmission Line Model with Exponential Decay (MTLE) and for dierent channel heights the results for lightningelectromagnetic field (LEMF) at dierent distances fromthe channel-base are presented in this paper, so as for the spatial and temporal current distribution along the channel. The decay constant influence on LEMF above perfectly conducting ground is analyzed using new lightning channel-base current function and MTLE as an engineering model for a lightning return stroke. The proper choice of this constant can be made based on experimental results but also on the analysis of its influence on electric and magnetic field values and their shape characteristics.