The relationship between the derivative of LEMP in near-field on the surface of ground and that of channel-base current of lightning return stroke

The results by accurately calculating with dipole method show that the waveform of the derivative of the electric field and waveform of the derivative of approximate calculation are consistent within 50 meters; and the derivative of the waveform of the magnetic field and the derivative waveform of approximate calculation are consistent within 200 meters.