Accession Number : AD0717685

Title :   Forward and Back Scatter Characteristics of Spherically Symmetric Overdense Clouds for Several Electron Density Distributions.

Descriptive Note : Environmental research papers,

Corporate Author : AIR FORCE CAMBRIDGE RESEARCH LABS L G HANSCOM FIELD MASS

Personal Author(s) : Klein,Milton M.

Report Date : 23 NOV 1970

Pagination or Media Count : 21

Abstract : Knowledge and understanding of the propagation of electromagnetic waves through the ionosphere, ionspheric irregularities, and artificial electron clouds, provide the information and criteria needed to solve Air Force problems of discrimination, detection, and communication. Because the electron density distribution changes during expansion of a cloud, it is desirable to know how the change affects the scattering characteristics of the cloud. A determination, in geometric optics approximation, of the forward and backscatter characteristics of spherical overdense clouds having: (1) a gaussian decrease with distance from the center, (2) a sech squared, or exponential, decay, and (3) an inverse-squared decrease, showed that the back scatter cross section for the inverse square distribution is always larger than for the other two distributions. As the center point density increases, the back scatter cross section obtained with the gaussian sphere most rapidly takes on the characteristics of a conducting sphere, that of the sech squared distribution lags slightly behind, but that of the inverse-square sphere never gets close to the result for a conducting sphere. In forward scatter, the inverse-square distribution shows the largest cross section and a fairly rapid increase with center point density, the sech squared distribution has an essentially constant cross section, and the gaussian, which has the lowest forward scatter cross section, shows a slight decrease with center point density. (Author)

Descriptors :   (*IONOSPHERIC PROPAGATION, BACKSCATTERING), ELECTRON DENSITY, RADIO WAVES, RADIOFREQUENCY INTERFERENCE, APPROXIMATION(MATHEMATICS), DISTRIBUTION FUNCTIONS

Subject Categories : Radiofrequency Wave Propagation

Distribution Statement : APPROVED FOR PUBLIC RELEASE