COMPUTATIONS OF ELECTROMAGNETIC FIELDS RADIATED FROM COMPLEX LIGHTNING CHANNELS

In this paper, three methods for calculating electromagnetic fields radiated from complex lightning channels are discussed, which includes channel obliqueness, branches and tortuosity. By rotating and moving the coordinate system of the vertical channel, differential expressions of electromagnetic fields from the irregular channel can be derived from the conclusions of the straight and vertical channel. Through analyzing calculation results of two examples reveals that channel tortuosity and branch is to introduce the higher frequency content above 100 kHz into lightning electromagnetic fields.