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Electromagnetic Waves in Turbulent Media

#G-1376


Development and Application of Electromagnetic Waves Propagation in a Turbulent Anisotropic Absorptive Media

Tech Area / Field

  • PHY-PLS/Plasma Physics/Physics
  • INF-COM/High Performance Computing and Networking/Information and Communications
  • INF-OTH/Other/Information and Communications
  • INF-SIG/Sensors and Signal Processing/Information and Communications
  • INS-MEA/Measuring Instruments/Instrumentation
  • PHY-RAW/Radiofrequency Waves/Physics

Status
8 Project completed

Registration date
05.12.2005

Completion date
18.06.2010

Senior Project Manager
Safronova O N

Leading Institute
Georgian Technical University, Georgia, Tbilisi

Collaborators

  • University of Washington / Department of Electrical Engineering, USA, WA, Seattle

Project summary

The main goals of this project are: experimental investigation of statistical characteristics of scattered electromagnetic (EM) waves on the bases of creating new device–measuring complex of equipments, development of both analytical calculation and numerical simulation of statistical characteristics of scattered HF radiation by randomly inhomogeneous absorptive anisotropic layer in the low atmosphere; generalization of Kotelnikov–Shannon’s formula; creation of new mechanism of ULF planetary-scale EM waves generating in different ionospheric layers.

Calculation of statistical moments of the angular power spectrum (APS) of scattered microwaves at different location of link (source-receiver) with respect to the absorptive randomly inhomogeneous plane layer will be carried out. We expect to reveal new effects due to joint influence of absorption and anisotropy in the low atmosphere taking into account external magnetic field. New features of the “effect of compensation”, which has been revealed by us recently, and the evolution of the APS of HF EM waves scattered by plane layer of turbulent anisotropic collisional magnetoplasma will be investigated.

Construction of the new device–measuring complex of equipments working in the frequency band 10 GHz measuring synchronously fluctuations of amplitude, phase progression and angle–of–arrival of scattered microwaves and meteorological measurements. Both round–the–clock and seasonal investigation of these fluctuations on ground surface and above–water links from a few hundred meters up to few kilometers will be carried out.

Generalization of Kotelnikov–Shennon’s formula, allowing to achieving higher accuracy of reproduction of a signal and highly noise stability will be carried out. Restoration of stochastic signal (field) on the bases of sampling of a stochastic signal (filed) in discrete points will be considered.

Expected results. The new equipment will enable to estimate character of turbulence not by indirect measurement (of amplitude and angle–of–arrival) but on direct measurement of all statistical parameters: amplitude, phase progression and angle–of–arrivals of scattered microwaves. Experimental investigations guess synchronous measurements of both amplitude and phase progression of microwaves as well as meteorological parameters: temperature, humidity, atmospheric pressure, speed and direction of the wind.

Investigation of the features of experimentally measured statistical moments of scattered microwaves in the geometrical optics (GO) and narrow band of angle approximations. Both broadening of the APS and displacement of its center of gravity of scattered HF EM waves versus: absorption, anisotropy, different orientation of an external magnetic field and different angle of inclination of a line–of–sight with respect to the turbulent plasma layer will be considered. The source and receiver are located on the opposite sides with respect to a randomly inhomogeneous layer. Numerical simulation of the APS will be carried out using the Monte Carlo method. The “angle of compensation” at which two asymmetric factors (oblique illumination and medium anisotropy) completely compensate each other will be found for different layers of the ionosphere. In this case the center of gravity of the APS does not displace and the spatial spectrum not broadens. Numerical simulations will be carried out by Monte–Carlo method. We expect to reveal new effects due to joint influence of absorption and anisotropy in the low atmosphere taking into account inclination of an external magnetic field.

Restoration of continuous signals (TV signals, radio signals) by means of registration of discrete samplings will be investigated. Generalized Kotelnikov–Shennon’s formulae will be obtained for complex variable. They will be submitted as stochastic functional series. The highly effective generalized formula of samplings will be expressed as the infinite series and it can be applied for more exact transfer of continuous signals on various distances. The residual term of this series will be estimated by different asymptotical methods. The obtained formulas will have highly speeded of convergence in comparison with the well known Kotelnikov–Shannon’s formula. They will be valid for deterministic class of nonstationary stochastic processes including harmonized processes and, in particular, for stationary stochastic processes.

Physical and mathematical (linear and nonlinear) models of the influence of both ionized components of plasma and geomagnetic field on creation of nonlinear solitary vortices in the ionospheric plasma will be suggested. New mechanism of both generation of ULF planetary-scale EM waves and self organization of nonlinear vortex structures of these waves in different layers of the ionosphere will be submitted. The amplitudes, spatial scales, velocity of propagation and various dynamical characteristics of these structures will be calculated. Dynamic of these large-scale wavy structures will be considered in β- approximation using nonmodal mathematical analyses. Linear wave processes of energy transfer between flows and perturbations, inter-transformation between the waves and modes and other mechanisms will be investigated using nonmodal approximation.

Practical significance. The obtained results may be widely applied in radiolocation. Knowledge of the features of radio waves propagation will take into account the errors of coordinates of target location caused due to their propagation. Similar aspects are typical in radio–navigation. Knowledge of the laws of variation of phase characteristics of EM waves allows to design optimal telecommunication systems, using new and progressive methods of HF multilayer phase manipulation. The purposes of simulation is update theory of microwaves propagation and derive convenient engineering formulas for design of various radio systems and construction of different radio engineering systems for various purposes. The obtained results allow to predict and design the appropriate radio–technical systems, to reach principally high quality of these measured systems. We intend to give recommendations of construction of the phase radio–technical systems and recommendations of solution of the problems for ecological monitoring of the region. Increasing quality of characteristics of radio–technical systems is in principle new approach for the solution of many application problems, which makes this project attractive in commercial point of view. Compensation effect, in our point of view, will have great practical application in satellite communications and remote sensing of both artificial and natural plasma inhomogeneities by the translucence methods. Generalized Kotelnikov–Shannon’s formula can be applied for restoration of continuous signals (TV signals, radio signals) registering by recipient by means of discrete samplings. Interested parties may be Telecom, firms specializing in production, industry and application of navigation equipments, especially GPS, radio location systems. Globally in decisions of these problems are engaged NASA, Ukraine–cosmos and so on. Some results may be applied in diagnostic of parameters of randomly inhomogeneous ionosphere, cosmic and laboratory plasma; modification of remote sensing methods and algorithms; description of X-ray scattering on molecules of thermotropic and liotropic liquid crystals, ultraviolet light scattering by chloroplast. They will have practical application in medicine, particularly in revealing of the reasons of pathological complications in people by ULF electromagnetic precursors caused due to natural hazard (earthquake, volcano, tsunami and other).


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