MEASUREMENTS OF LIGHTNING RADIATION FIELD AND ESTIMATION OF FIRST RETURN STROKE PARAMETERS

This paper briefs a method of measuring lightning radiation field with a fast antenna and narrow bandwidthreceivers, the first return stroke parameters and the spectrum distribution from 2 kHz to 20 MHz for bothground discharges and cloud discharges are calculated. The peak radiation field of first return stroke, normalized to 50 km, is (15.2±8.4)V/m. Below 1 MHz, thetotal energy radiated by the first return stroke is (0.8±1.6)×10~5J, the peak power is (0.8±1.0)×10~10W, thepeak current is(27.8±17.1)kA, and the peak current derivation is (109.3±91.5) kA/μs. The peak spectral amplitudes appear between 4 kHz to 10 kHz for ground discharges and 20 kHz to 80kHz for cloud discharges. From 10 kHz to 3.0 MHz, the spectral amplitudes of the ground discharges decreasein 1/f, and from 3.0 MHz to 20 MHz, in 1/f~2. Below40 kHz, the ground discharge is the main lightningradiation source; and above 40 kHz, both discharges behave similarly. A few special phenomena were found and explained preliminarily.

MEASUREMENTS OF LIGHTNING RADIATION FIELD AND ESTIMATION OF FIRST RETURN STROKE PARAMETERS