| The rapid development of communication technology has meet various needs of people increasing since twenty-first Century.However,with the development of industrial production and the shortage of resources,in recent years,more attention has been paid to wireless communication in lossy media such as rock,ice,sea water and so on.For example,it is used in mine emergency communication,underwater wireless sensor network communication,water surface remote control Underwater Unmanned boat,and submarine communication and so on.Nevertheless,the attenuation of the permeable electromagnetic wave in a lossy medium increases significantly with the increase of the frequency of the electromagnetic wave.In order to realize the communication in the lossy medium effectively,it is of great significance to study it intensively.This article will begin with the basic theory,study the electromagnetic parameters and dipole antennas in the lossy media.What's more,a set of hardware system for measuring electromagnetic parameters will be designed.On the basis of the hardware system of measuring electromagnetic parameters,a communication system worked in lossy medium will be completed by using 2DPSK modulation and demodulation.The main contents of this paper are the following aspects.(1)First of all,several basic electromagnetic parameters in the lossy medium are introduced,the relationship between electromagnetic wave length,rate and frequency in sea water is simulated and analyzed by MATLAB according to the formula.On this basis,the galvanic dipole and the magnetic dipole model in the large wireless media are established,and the propagation characteristics of the electromagnetic field are simulated and analyzed.(2)With the electromagnetic field integral expression in the air produced by the electric dipole in the sea,which contains the Bessel integral,it could be simplified by using the characteristics of electromagnetic parameters and the integral table in the sea water.The mathematical model of its propagation characteristics is established,which provides a theoretical basis for the subsequent implementation of cross media communication.(3)A design of physical test system for the two layer medium of sea-air is designed,it includes the watertight housing design,power amplifier design,antenna optimization design and impedance matching design,etc.On this basis,the electromagnetic field propagation characteristics of the two layer medium of sea water air are tested by different forms of antenna.The comparison and analysis are made with the theoretical results,which provide theoretical and experimental basis for the realization of wireless communication in the lossy medium.(4)A wireless communication system was designed and implemented for the sea-air two layer medium channel.It includes modulation,demodulation,channel coding and decoding,synchronization system and analog circuit system,etc.And the field wireless communication test was carried out,the transmission of cross media wireless information was realized.The expected effect was achieved,and the feasibility of using electromagnetic signal to communicate across the medium was verified. |
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