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Radio Waves in the Low Atmosphere

#G-1752


Wavy Processes in the Lower Atmosphere and Development of Measuring Equipments for Investigation of Statistical Characteristics of Scattered Radio Waves

Tech Area / Field

  • PHY-RAW/Radiofrequency Waves/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-DET/Detection Devices/Instrumentation
  • INS-MEA/Measuring Instruments/Instrumentation
  • OBS-NAT/Natural Resources and Earth Sciences/Other Basic Sciences
  • PHY-PLS/Plasma Physics/Physics

Status
3 Approved without Funding

Registration date
18.05.2009

Leading Institute
Georgian Technical University, Georgia, Tbilisi

Collaborators

  • Chungnam National University, Korea, Daejeon\nUniversity of Nevada / Department of Electrical and Biomedical Engineering, USA, NV, Reno\nKyushu University / Department of Computer Science and Communication Engineering, Japan, Fukuoka\nUniversity of Washington / Department of Electrical Engineering, USA, WA, Seattle\nKorea Maritime University, Korea, Busan\nTokyo Institute of Technology / Department of Electrical and Electronic Engineering, Japan, Tokyo\nUniversity of Cologne / Rhenish Institute for Environmental Research, Germany, Cologne

Project summary

Construction of the new microwave measuring set of equipment continuously controlling reflection coefficient of radio engineering antenna block and automatic matching of this system with medium is one of the main goals of this Project. This set of equipments has no analogues will have great practical and commercialization interest (see below). It will be characterized by: small dimensions and weight; high measurements accuracy; high measuring stability; built-in possibility of this device in the radio engineering systems having different applications (radar, space communication, mobile communication, etc.); will have: low cost and high metrological characteristics. Objects locating near antenna-transmitting device make essential influence on radio-waves propagation in the 500…2000 MHz frequency band. Control method with negative phenomena can be achieved measuring the antenna block complex reflection coefficient (CRC) at radio-transmitting device monitoring and automatic matching of the chain with mismatching process. Microwave measuring converter built-in the antenna-feeder chain of the radio engineering system output of which generates signals carrying CRC information is the bases of the matching adaptive system offered in this Project. Threshold value of the reflection coefficient and a power level are regulated by customer request. This device could be applicable for continuous monitoring of antenna block CRC of radio engineering system and for automatic matching with medium at electromagnetic waves propagation in the 500…2000 MHz frequency band. Modernized microwave units CRC measurement offering in this project will solve measuring problem without power sensors application, substantially increase stability and accuracy of the CRC module and argument measurements. Main goals of the Project are: Elaboration of the parametrical measurement method of the microwave units CRC of the radio engineering system antenna-feeder chain. This method should provide creation of compact and inexpensive measuring converters having high accuracy and stability at influence of various destabilizing factors (temperature, radiation, humidity, etc.); Synthesis of the concrete parametrical microwave measuring converters on the bases of the generalized mathematical model for its application in the antenna block CRC monitoring of the radio transmitting equipment and adaptation of this block to the medium at radio waves propagation using automatic matching in the operating frequency band, Estimation of the metrological characteristics (broadbandness, accuracy, stability, speed, etc.) of the synthesized microwave converters. The influence of the destabilizing factors (temperature, radiation, humidity, etc.) on the CRC module and argument measuring errors of the parametrical microwave measuring converter; Elaboration of both processing algorithms of a measured information and calibration algorithms for theirs application to the built-in equipments at complicated meteorological conditions (temperature, humidity, atmospheric pressure) and mechanical effect (vibration, jolt, stroke, etc.); Simulation of the microwave measuring converter units; Manufacture of the microwave measuring converter test samples and theirs experimental investigation; Investigation of the influence of foreign objects and fluctuations of turbulent atmosphere refraction coefficient on the matching of a transmitting device antenna-feeder chain with medium. This system will provide minimization of the reflected waves exciting in the antenna-feeder chain. Project participants have scientific experience on investigation and elaboration similar measuring equipments. New device will have commercialization interest for: manufacturers of microwave equipments having different special purposes, manufacturing planners developing antenna-feeder chains of radio engineering systems. Designers and manufacturers of microwave chains and communication networks are interested in low-cost microwave measuring devices (Scientific production association “Svetlana” Sankt-Peterburg, Russia; Scientific production company “Micran”, Tomsk, Russia; Research institute “Orion”, Kiev, Ukraine; Scientific production association “Saturn”, Kiev, Ukraine; Limited company “Kvant-efir”, Kiev, Ukraine), Designers and manufacturers of the space technology interested in the acquisition of space communication system microwave chains parameters (Scientific production association S.A. Lavochkin, Khimki, Russia; Design office “Yuzhnoe”, Dnepropetrovsk, Ukraine;), National cosmic agency of different countries (NASA, USA; Russian Cosmos, Russia; Ukraine Cosmos, Ukraine), Manufacturers of mobile communication systems including the equipments of the ground-based stations and mobile telephones interested in the adaptation of the communication systems to the microwave units’ parameters, to the propagation condition and theirs influence on the external objects (Huawei Technologies Ltd company, China; Nokia-Siemens-Network company, Finland, Germany; Samsung Electronics Co. Ltd, South Korea; Motorola inc., company, USA).

New multi-channel equipment measuring signal amplitude and phase progression along opened links at difficult conditions taking into account natural and artificial obstacles, turbulence in the lower atmospheric layer will be constructed. This equipment will not have analogues and based on the homodyne method measuring amplitude, phase progression and the angle of arrival fluctuations of the scattered microwaves at indoor/outdoor propagation along open links having arbitrary configuration. This method is supported by patents. Experimental investigations of microwave propagation in difficult conditions will have exclusive uniqueness as multi-channel measurements of microwaves phase progression were never carried out over opened links. This equipment will permit: meteorological measurements in different places of the communication link in the lower atmospheric layer; meteorological and electrical synchronous measurements; estimation of the measured metrological parameters and phase progression; experimental investigations of microwave propagation in buildings, constructions containing obstacles and interferences. New measuring equipment will allow carry out testing (certification) of buildings, constructions, adjacent territories for organization telecommunication system. All measuring data will be registered periodically in the computer memory. These models will in a short time certificate buildings, constructions and adjacent territories and therefore these models have commercial advantage. Mathematical model of the microwave indoor/outdoor propagation will be elaborated in a framework of this Project. This model will take into account as obstacles as well as turbulence of the lower atmospheric layers. Developing of Multiple-Input, Multiple-Output (MIMO) conception, recommendations and its application for organization of new telecommunication system will be offered in this Project. The obtained results will have high demand for: telecommunication systems designers and users; mobile communication organizers; wireless computer network organizers; telemetry, command control systems, radio navigation, radar, remote sensing.

Basic research of the project is devoted to investigation of: peculiarities of electromagnetic waves propagation and scattering; wavy processes in lower turbulent atmospheric layers and the features of low atmosphere at different altitudes above the Earth surface. Absorption has a substantial influence on statistical characteristics of scattered radiation. Therefore in this project we shall investigate: the influence of medium absorption coefficient on statistical characteristics of scattered spatial-bounded radiation at propagation in low turbulent atmosphere using the smooth perturbation method; new features of the angular power spectrum (APS) or brightness of scattered electromagnetic waves in lower atmospheric layers which have practical application in radio sighting and navigation. Novelty of the project is analytical and numerical investigations of evaluation of experimentally observed APS in lower turbulent absorptive atmospheric layers using complex geometrical optics, smooth perturbation method and narrow angle approximations. Calculation of statistical moments of the APS (broadening and displacement of its maximum) of scattered microwaves by turbulent layers when permittivity is a random function of both spatial coordinates and time is one of the main goals of this project. Statistical characteristics of experimentally observable APS of scattered microwaves can be measured by receiving ground-based or satellite antennas. Experimetally measured MHz frequency band statistical moments allow to estimate spatial-temporal scales of fluctuating parameters of inhomogeneous absorptive layer, which are very important in geophysics, remote sensing (such experiments are carried out intensively in USA, France, Russia and Japan) and also in communication. The source, radiating high-frequency electromagnetic waves, and the receiving antennas are located in opposite sides with respect to scattered layer is of interest from the point of view of its practical application. Nonstationary stochastic processes taken into account spatial-temporal variations of permittivity fluctuations and the geometry of the task will be investigated for the first time. The features of the APS of multiply scattered radiation and its statistical moments versus: thickness of a layer, absorption coefficient, distances of the source and the receivers with respect to scattered absorptive turbulent layer and for different anisotropic correlation spectral functions of medium irregularities we shall investigate analytically and numerically. Well approved numerical methods and statistical simulation (Monte-Carlo method) will be carried out using satellite and remote sensing experimental data. We shall give the recommendations of theirs practical applications. The peculiarities of spatial-temporal medium parameters fluctuations will be established using empirical and dimensional methods. “Compensation effect”, discovered by us, will be considered for lower turbulent atmospheric layers where three asymmetric factors (inclined incidence, absorption and anisotropy) compensate each other. Knowledge of the “compensation angle” is very important in a low atmosphere for information transfer at great distances with small losses. New statistical model of turbulent diffusion of passive impurity in a turbulent stream will be submitted in the project for lower turbulent atmospheric layers. Analytical expression for effective turbulent diffusion coefficient will be obtained taking into account both molecular and turbulent diffusions. Transversal and longitudinal diffusion coefficients will be calculated. Exact solution of nonlinear equation of motion taking into account wind effects in turbulent near the ground surface layers; analytical expression of turbulent viscosity coefficient will be obtained. Well known Samarski-Sobol method will be applied for the solution of nonlinear nonstationary diffusion equation. Analytical expression of permittivity fluctuations containing fluctuating weather parameters (humidity and temperature) will be obtained for lower turbulent atmospheric layers. Buoyancy effects will be taken into account calculating lower turbulent atmospheric characteristics and constructing corresponding altitude-distributive curves (so-called vertical profiles). Full system of empirical formulae will be offered for weather fluctuating parameters (kinetic energy, pressure and temperature spectral functions) in tropospheric layers. Using these formulas characteristic linear scales, turbulent coefficients and characteristic life times of turbulent areas will be calculated which are very important at millimetre wavelength wave’s propagation in media with high humidity. Diffusion equation will be solved using new methodDolidze method. Diffusion coefficient determines relaxation diffusion time, which allows restoring thickness of turbulent layers at different weather parameters. New mechanism of turbulence generation by internal gravity waves will be offered within the scope of this project. These waves are generated due to the Earth’s surface geometry and can propagate up to 80 km altitudes where they broken and generate one of the power source of turbulence. Nonstationary model describing this process will be submitted. Weather parameters are depend on altitude (vertical gradients are nonzero) in lower atmospheric layers and can be substantially vary. Corresponding analytical formulae describing curvature of electromagnetic waves trajectories at propagation in lower atmospheric layers with different gradient parameters (humidity and temperature) will be offered in the project. The obtained results will be published in refereed scientific journals and international symposium keeping all Copyrights Agreements.


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