摘要
This paper briefs a method of measuring lightning radiation field with a fast antenna and narrow bandwidth receivers, the first return stroke parameters and the spectrum distribution from 2 kHz to 20 MHz for both ground 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, the total energy radiated by the first return stroke is (0.8±1.6)×10~5J, the peak power is (0.8±1.0)×10~10W, the peak 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 80 kHz for cloud discharges. From 10 kHz to 3.0 MHz, the spectral amplitudes of the ground discharges decrease in 1/f, and from 3.0 MHz to 20 MHz, in 1/f^2. Below40 kHz, the ground discharge is the main lightning radiation source; and above 40 kHz, both discharges behave similarly. A few special phenomena were found and explained preliminarily.
This paper briefs a method of measuring lightning radiation field with a fast antenna and narrow bandwidth receivers, the first return stroke parameters and the spectrum distribution from 2 kHz to 20 MHz for both ground 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, the total energy radiated by the first return stroke is (0.8±1.6)×10~5J, the peak power is (0.8±1.0)×10~10W, the peak 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 80 kHz for cloud discharges. From 10 kHz to 3.0 MHz, the spectral amplitudes of the ground discharges decrease in 1/f, and from 3.0 MHz to 20 MHz, in 1/f^2. Below40 kHz, the ground discharge is the main lightning radiation source; and above 40 kHz, both discharges behave similarly. A few special phenomena were found and explained preliminarily.
