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Title: Comparison of the RF frequency spectra of HEMP and lightning. Technical report, 22 Sep 87-10 Jul 90

Cloud pulses are much more common than these earlier studies indicate. Our spectra of the largest overhead cloud pulses are nearly parallel to but significantly below the HEMP spectrum from 1 MHz to 50 MHz, while obtained from lighting tens of kilometer offshore over salt water show faster relative decay with increasing frequency, are significantly below ours between 10 and 50 MHz, and are about equal to ours between 3 and 10 MHz. The shortest rise time to initial peak value of overhead lighting pulses are of the order of 0.3 micro sec. A broader bandwidth system than that used would allow measurement of the rapid field variation occurring throughout the cloud pulses associated with frequencies above abut 50 MHz but would observe essentially the same risetime to initial peak. That is, the higher frequency content of the cloud pulses is contained in the rapid field variation throughout the overall waveforms and not in the initial rise to peak value.
Authors:
Publication Date:
OSTI Identifier:
5399116
Report Number(s):
AD-A-234306/9/XAB
CNN: DNA001-87-C-0180
Resource Type:
Technical Report
Research Org:
Florida Univ., Gainesville, FL (United States). Dept. of Electrical Engineering
Country of Publication:
United States
Language:
English
Subject:
45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE; ELECTROMAGNETIC PULSES; SPECTRA; CLOUDS; COMPARATIVE EVALUATIONS; DECAY; LIGHTNING; PULSES; VARIATIONS; WATER; ELECTRIC DISCHARGES; ELECTROMAGNETIC RADIATION; EVALUATION; HYDROGEN COMPOUNDS; OXYGEN COMPOUNDS; RADIATIONS 450200* -- Military Technology, Weaponry, & National Defense-- Nuclear Explosions & Explosives