Transport methods have been employed to study the propagation of a narrow-angle electromagnetic beam through a turbulent medium. Results are presented for the mean-square angular divergence of the beam, cross section of the beam, and the power received by a planar aperture in the medium. The problem of back-scattered radiation is also considered and results are obtained which reduce, in the limit of zero true absorption, to previous results. (Author).
In this report the author has reviewed the recent developments on beam propagation in a turbulent medium. These include the effect of the turbulence on beam intensity, spread, coherence, wander, angle of arrival, scintillation and distortion, as well as other related topics.
Electrical Engineering Wave Propagation and Scattering in Random Media A volume in the IEEE/OUP Series on Electromagnetic Wave Theory Donald G. Dudley, Series Editor This IEEE Classic Reissue presents a unified introduction to the fundamental theories and applications of wave propagation and scattering in random media. Now for the first time, the two volumes of Wave Propagation and Scattering in Random Media previously published by Academic Press in 1978 are combined into one comprehensive volume. This book presents a clear picture of how waves interact with the atmosphere, terrain, ocean, turbulence, aerosols, rain, snow, biological tissues, composite material, and other media. The theories presented will enable you to solve a variety of problems relating to clutter, interference, imaging, object detection, and communication theory for various media. This book is expressly designed for engineers and scientists who have an interest in optical, microwave, or acoustic wave propagation and scattering. Topics covered include: Wave characteristics in aerosols and hydrometeors Optical and acoustic scattering in sea water Scattering from biological materials Pulse scattering and beam wave propagation in such media Optical diffusion in tissues and blood Transport and radiative transfer theory Kubelka—Munk flux theory and plane-parallel problem Multiple scattering theory Wave fluctuations in turbulence Strong fluctuation theory Rough surface scattering Remote sensing and inversion techniques Imaging through various media About the IEEE/OUP Series on Electromagnetic Wave Theory Formerly the IEEE Press Series on Electromagnetic Waves, this joint series between IEEE Press and Oxford University Press offers outstanding coverage of the field with new titles as well as reprintings and revisions of recognized classics that maintain long-term archival significance in electromagnetic waves and applications. Designed specifically for graduate students, practicing engineers, and researchers, this series provides affordable volumes that explore electromagnetic waves and applications beyond the undergraduate level. See page il of the front matter for a listing of books in this series.
The most recent developments on the propagation of microwave and optical beams in turbulent media, such as the clear atmosphere are discussed. Among the phenomena considered are beam spreading, beam wander, loss of coherence, scintillations, angle-of-arrival variations, and short pulse effects. Also included is a discussion of methods of compensation of the effect of turbulence on communications and imaging systems.
Using transport theory the mutual coherence function of a beam propagating in a turbulent medium has been studied in detail, including the effect of the beam size, focal length and strength of the turbulence. The most detailed results are obtained for the MCF when the fluctuations have a Gaussian spectrum, but simple closed-form asymptotic results have also been obtained when the spectrum is a von Karman. (Author).
This is a concise, unified exposition of the existing methods of analysis of linear stochastic waves with particular reference to the most recent results. Both scalar and vector waves are considered. Principal attention is concentrated on wave propagation in stochastic media and wave scattering at stochastic surfaces. However, discussion extends also to various mathematical aspects of stochastic wave equations and problems of modelling stochastic media.
The mutual coherence function of a laser beam propagating in turbulence with a modified von Karman spectrum for the index of refraction fluctuations, including a parametric study of the effect on the MCF of varying beam size, focal length, and the properties of the turbulence was computed. The results are valid over all propagation distances, unlike calculations employing the method of smooth perturbations. Also studied was the effect of a constant wind on the frequency spectrum of signal. It was found that over most practical path lengths the spectral width is delta omega = 4.1V ((k sub o)sup 6/5)(z sup 3/5)((C sub n, sub 2)sup 3/5), where V is the wind speed, k sub o is the signal wavenumber, C sub n sup 2 is the strength of turbulence, and z is the path length in the turbulence. (Modified author abstract).
