Accession Number : AD0624708

Title :   ELECTROMAGNETIC SHIELDING EFFECTIVENESS MEASUREMENTS USING LOW CONDUCTIVITY CLOSED SURFACES.

Descriptive Note : Rept. for Jun-Sep 64,

Corporate Author : NAVAL CIVIL ENGINEERING LAB PORT HUENEME CALIF

Personal Author(s) : Lasiter,H. A.

Report Date : DEC 1965

Pagination or Media Count : 30

Abstract : In an investigation to predict the shielding effectiveness of low-conductivity materials used in electromagneticinterference-shielded structures, the symmetrical configuration of a spherical shell was adapted to approximate the closed walls of a normally cubical or rectangular shielded enclosure. A hemisphere was used for the experiments and a half cube with the same surface area and conductivity (0.1 mho/meter) was used for comparison of an equivalent rectangular structure. In measurements over a frequency range of 20 to 900 Mc (or MHz), the half cube showed a greater shielding effectiveness than the hemisphere over a major portion of the frequency range. The primary advantage of the hemisphere is the ability to predict the absorption over a wide band of frequencies. The conductivity of the materials used in this investigation was found to exhibit an empirical relationship with frequency range, described by log (sigma/sigma sub dc) = 0.236 log f. (Author)

Descriptors :   (*ELECTROMAGNETIC SHIELDING, EFFECTIVENESS), MEASUREMENT, ATTENUATION, WALLS, HEMISPHERICAL SHELLS, RECTANGULAR BODIES, HIGH FREQUENCY, VERY HIGH FREQUENCY, ULTRAHIGH FREQUENCY

Subject Categories : Electrical and Electronic Equipment

Distribution Statement : APPROVED FOR PUBLIC RELEASE