• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.53 no.6
• /
• pp.330-336
• /
• 2004

In this work, in order to obtain the detailed information about lightning electromagnetic pulses, the electric fields radiated from multiple lightning return strokes were measured and analyzed statistically. The electric field measuring system consists of a hemisphere antenna of 30cm in diameter, integrator and data acquisition device, and its frequency bandwidth ranges from 200Hz to 1.56MHz, and the sensitivity is 0.96㎷/V/m. The electric field signals are digitized every 200ns with the transient signal analyzer having the resolution of 12-bit and the recording length of 5 kilowords and are registered at personal computer. As a result, the electric fields produced by the first return stroke begin with a slow initial part or front, which starts just after or during the last stepped leader. On the average the rise times of the electric fields for the positive first, second and third strokes are 4.21${\mu}\textrm{s}$, 3.94${\mu}\textrm{s}$ and 2.75${\mu}\textrm{s}$, respectively, and those for the negative first, second and third strokes are 3.46${\mu}\textrm{s}$, 3.15${\mu}\textrm{s}$ and 2.79${\mu}\textrm{s}$, respectively. The zero-crossing times of the electric fields for first return strokes range from about 10 to 80${\mu}\textrm{s}$. The mean zero-crossing times for subsequent return strokes are shorter than those for first lightning return strokes.

• Proceedings of the KIEE Conference
• /
• 1999.07e
• /
• pp.2158-2160
• /
• 1999

In order to obtain the detailed informations about the lightning electromagnetic fields, the electric and magnetic fields radiated by lightning return strokes were observed with the electric field sensor of hemi-sphere type and the magnetic field sensor of loop type and their physical characteristics were statistically analyzed. The multiple stroke occurrence numbers was 2.6. In multiple lightning strokes the amplitude of peak and the time interval between the subsequent strokes were decreased as the number of the subsequent strokes increases.