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Electromagnetic Waves Propagation in Atmosphere

#G-1914


Development of Theoretical Simulation of Scattered Electromagnetic Waves by Turbulent Atmospheric Slabs and Experimental Investigation of Statistical Characteristics of This Radiation Using Designed Unique Measuring Equipment

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
01.03.2011

Leading Institute
Georgian Technical University, Georgia, Tbilisi

Collaborators

  • Ariake National College of Technology, Japan, Fukuoka\nUniversity of Washington / Department of Electrical Engineering, USA, WA, Seattle\nUniversity of Nevada / Department of Electrical and Biomedical Engineering, USA, NV, Reno

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. The solution of this problem will allow carrying out continuous monitoring of the chain state and also automatic matching of the antenna with environment leading to the increase radio engineering system reliability and accuracy of transmitted data. Foreign objects locating near antenna-transmitting device also make essential influence on radio-waves propagation in the 500…2000 MHz frequency band. These objects scatter and reflect radio waves in the opposite direction. Reflected wave excites in the radio system antenna-feeder chain which could be registered by device. Control method with negative phenomena includes adaptation of the transmitting antenna-feeder chain of radio engineering system to the environment parameters and can be achieved by continuous measurement of the antenna block complex reflection coefficient (CRC) at radio-transmitting device monitoring and at synchronous automatic matching of the chain with mismatching process on the basis of monitoring results. 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. Alarm formation is provided in two cases: at exceeding given value of the reflection coefficient module and at decreasing power level in the microwave chain below given power level. 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 at electromagnetic waves propagation in the 500…2000 MHz frequency band. Modernized microwave units CRC measurement offering in this project will substantially increase stability and accuracy of the CRC module and argument measurements without power sensors. Main goals of the Project are: Elaboration of measurement method of the CRC in antenna-feeder chain. Design compact measuring converter having high accuracy and stability (at the influence of temperature, radiation, humidity, etc.); Elaboration of the generalized mathematical model of the measuring parametrical microwave converter adequately describing correlation of the output converter voltage samplings with the measured parameters and own converter characteristics allowing to exclude the influence of these characteristics on the measurement results applying calibration; 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; Elaboration of both processing and calibration algorithms for estimation of temperature, humidity, atmospheric pressure, vibration, jolt, stroke, etc.; Simulation of the microwave measuring converter units for minimization of their influence on the wavy processes in the chain; Manufacture of the microwave measuring converter test samples and theirs experimental investigation. Test measurements of the microwave two-pole parameters for metrological certification of the constructed device.; 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, and elaboration of the automatic matching system. This system will provide minimization of the reflected waves exciting in the antenna-feeder chain due to the influence of both foreign objects and atmosphere parameters fluctuations. 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).

Construction of unique multi-channel equipment measuring amplitude and phase progression of microwave signal propagating along the open links taking into account natural and artificial obstacles, turbulence in the lower atmospheric layer. 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. The uniqueness of the measuring equipment is defined by the possibility of measurement of microwave signal phase progression on an open link of radio-waves propagation with possibility of calculation of phase cycles number arising at fluctuations of signal phase progression, caused by changes of electric link length. On such links the fluctuation of phase progression of a signal will not exceed the value of one phase cycle. On rather extended links the number of digits of phase difference measuring instrument within one phase cycle is expedient for choosing equal to 8, causing thus accuracy of measurement of microwave signal phase progression in value 1.4°. The mentioned measuring equipment is developed and partially made. The equipment is unique and anywhere in the world earlier was not applied. Methods of phase progression measurement are supported by series of 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 certification of buildings, constructions, adjacent territories for organization of telecommunication system revealing “dead zones”. All measuring data will be registered periodically in the computer memory with corresponding minute mark. The obtained information we be will preliminary processed using specialized controllers. These models will permit substantially shorten testing 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, radio navigation, radar and remote sensing.

Basic research of the project is devoted to investigation of: peculiarities of electromagnetic waves propagation and scattering in turbulent atmospheric layers at different altitudes above the Earth surface. Novelty of this project is the development of new effect “the influence of the directional fluctuations of an external magnetic field on the statistical characteristics of scattered radiation” discovered recently by us for different turbulent slabs taking into account specific factors characterizing this medium; “compensation effect”, discovered early by us, will be applied 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. Different analytical (complex geometrical optics and smooth perturbation methods, narrow angle approximation) methods. Well approved numerical methods and statistical simulation (Monte-Carlo method) will be applied using satellite and remote sensing experimental data. The main goals of this project are: a) calculation of statistical moments of the experimentally observable (by receiving ground-based or satellite antennas) APS (broadening and displacement of its maximum) or brightness of scattered electromagnetic waves by turbulent layers having practical application in radio sighting and navigation. Such experiments very important also in geophysics, remote sensing and are carried out intensively in USA, France, Russia and Japan. Source radiating high-frequency electromagnetic waves and the receiving antennas are located in opposite sides with respect to scattered layer. 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, anisotropy factor and the angle of inclinaton of prolae irregularities with respect to the externl magnetic field will be investigated analytically and numerically. Different anisotropic correlation spectral functions characterizing turbulent medium will be taken into account; b) investigation of the influence of medium absorption coefficient on statistical characteristics of scattered spatial-bounded radiation; c) new statistical model of the 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; d) buoyancy effects will be taken into account calculating lower turbulent atmospheric characteristics. Complete 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 waves’ propagation in the atmosphere with high humidity.

The obtained results will be published in refereed scientific journals and international symposium keeping all Copyrights Agreements.


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