| Most of the surface of the earth is covered by seawater,and every year we get enough seafood and marine deposits from the ocean.The development and utilization of marine resources is becoming more and more important in the development of various countries.The constant attention of countries to the maritime rights and interests also promotes the development of underwater communication technology.Low frequency radio waves are widely studied in submarine communication due to their stable and reliable propagation,but their wavelengths are prop ortional to the length of the antenna,and there is a great difficulty in the engineering realization.At present,it is widely used in acoustic communication.Now on the underwater wireless communication research international problem is that electromagnetic waves in the sea water transmission has a great attenuation that can not transmit long distance.Therefore,in order to make better use of radio waves for underwater communication,the research on underwater transmission characteristics of electromagnetic waves is necessary,and these characteristics are determined by the frequency characteristics of the dielectric constant.The complexity of the marine environment has also brought many difficulties to the research.First,the seawater is a weak conductive medium,and various oceanic dynamics in the ocean,such as ocean turbulence,sea waves and other ocean phenomena and ocean currents.And the geomagnetism is cut to produce a weak electric field,and the induced electric field can prompt the induced magnetic field.The weak electromagnetic field generated by seawater induction also affects the electromagnetic properties such as dielectric constant and conductivity of seawater.Therefore,it is very significant to study the seawater dielectric properties under static magnetic field on ocean electromagnetic exploration,marine remote sensing and underwater communication.In this paper,as the basic research work of underwater electromagnetic wave transmission,the frequency dependence on electrical characteristics of the main inorganic sea salt solution in seawater are studied deeply.Mainly including the following aspects:Firstly,the electromagnetic properties of seawater are analyzed in detail,and different seawater dielectric models are introduced in this paper.By comparing and analyzing the adaptation conditions and measurement methods of different models,we have proposed the model and experimental research methods used in this paper to study the dielectric properties of sea salt aqueous solution.As the sea water is weak conductivity medium,there is a certain conductivity,in the experiment we use a unique external circuit additional resistance method to make the circuit achieve impedance matching state in the RF.Secondly,we use the impedance analyzer to test the frequency dependence of dielectric characteristics and electrical conductivity characteristics of seawater salt solution under static magnetic field,and reveal the mechanism of the effect of static magnetic field on the dielectric and electrical conductivity characteristics of different salt in seawater.The experimental results show that the change trend of the complex permittivity of the seawater salt solution decreases with the increase of the measurement frequency with the effect of magnetic field.The value of the complex permittivity changes differently under magnetic fields.On the other hand,it is explained that the effect of magnetic field on the hydration process of different salt ions is different.Through the experimental data,we get a new relationship between the concentration and the dielectric constant by fitting the experimental data.The formula has wide applicability and is suitable for the solution before and after the static magnetic field.It is found that the influence of the magnetic field on the conductivity is due to the change of the thickness and electron mobility of the ion hydrate layer,which also leads to the change of the hydration radius.This study also provides a scientific basis for the further developme nt of underwater magnetic target detection and dispersion in electromagnetic wave detection.The current study of the permittivity of seawater is mainly to propose more accurate models suitable for complex marine environments.The frequency characteristics of the permittivity of seawater in the magnetic field environment are rarely studied,and the change of the permittivity is rarely explained from the microcosmic angle of ion hydration.Based on the theory and experiment,the frequency dependence on dielectric characteristics of seawater under static magnetic field are studied for the first time,and the relationship between dielectric constant and concentration is obtained.The study of dielectric constant and conductivity under magnetic field provides sc ientific basis for the study of underwater radio propagation and underwater magnetic target detection and scattering. |
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