Dissertation > Industrial Technology > Radio electronics, telecommunications technology > General issues > Basic theory > Radio wave propagation,the propagation mechanism

A Theory and Experiment Study of Composite Electromagnetic Scattering from Target over Different Scale Sea Surface

Author YeWenHua
Tutor WuZhenSen
School Xi'an University of Electronic Science and Technology
Course Radio Physics
Keywords Physical optics method High scale sea condition Grazing incident Composite electromagnetic scattering Sea clutter
Type Master's thesis
Year 2012
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Because of widely application of microwave remote sensing, sea measurement,oversea target detection and recognition, the study of EM composite scattering of targetover sea surface is more and more important. Thus, the characteristics of high-frequencycomposite electromagnetic backscattering from a conductor target abovetwo-dimensional sea surfaces are investigated. The main work is as follows:The high frequency approximation method PO(Physical Optic) which is used tocalculate the RCS(Radar Cross Section) of electrical large target is introduced;Themethod of target modeling, data processing and screen judging are presented;Numerical calculation of the RCS of different targets, and the results are in goodagreement with commercial software FEKO.The electromagnetic scattering characteristic of two-dimensional oceanic surface isstudied, two-dimensional surface is simulated by the Monte Carlo method, and theKA(Kirchhoff Approximation) method is applied for numerical computation, theinfluence of different wind speeds, different frequency and different polarization areanalyzed and discussed; The analytical method of SSA(Small Slope Approximation) oftwo-dimensional is used for the EM scattering characteristics of the sea, especiallywhen the incident wave in the sub-millimeter-wave. Then the surface element based ofPO method is applied to study the grazing incident with different sea surface area,different sea surface conditions, and different frequencies, the effect is good.There are two different methods to calculate the composite scattering of sea surfaceand target. The first method is employing the reciprocity theorem method to calculatethe coupling field of target and sea surface, and combining with the KA and the EEC(Equivalent Edge Currents) method to get the composite RCS of sea surface and target,the numerical result are in good agreement with experimental data; The second methodis using ray tracing method to simulate the multiple scattering between the surface andthe target, at last PO method is applied to calculate the total RCS, the numerical result isalso in good agreement with the experimental data.The statistical characteristics of two-dimensional dynamics sea clutter is studied.Several typical sea clutter models that described the amplitude distribution areintroduced, and some sea clutter parameter estimation methods are described. Focused on analyzing the clutter amplitude probability density distribution of time series, anddifferent parameters of the clutter data which clutter model fit in different sea situation.

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