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

Technical Report · Fri Mar 01 00:00:00 EST 1991

OSTI ID:5399116

Uman, M A

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.

• Research Organization: Florida Univ., Gainesville, FL (United States). Dept. of Electrical Engineering
• OSTI ID: 5399116
• Report Number(s): AD-A-234306/9/XAB; CNN: DNA001-87-C-0180
• Country of Publication: United States
• Language: English

Related Subjects

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