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Research On Characteristics And Structures Of Eqivalent Metamaterials

Posted on:2009-06-12Degree:DoctorType:Dissertation
Country:ChinaCandidate:L ChenFull Text:PDF
GTID:1118360272482197Subject:Electromagnetic field and microwave technology
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The newly discovery of left-handed material (LHM) has been regarded as one of the ten most significant discoveries in science community in 2003, and has been the front and focus area in physics and electromagnetics research. LHM is an electromagnetic artificial metamaterial with simultaneously negative equivalent permittivity and equivalent negative permeability. Compared with traditional materials, electromagnetic waves transmitted in such material will behave some fantastic phenomena, such as negative Snell refraction, reversed Dollper effect, reversed Cerenkov radiation, and so on. However, for the newly artificial electromagnetic materials, theories, numerical methods and applications of electromagnetic fields need to be developed.In classical electrodynamics, electromagnetic properties of mediums are described by the two macroscopical parameters: permittivity and permeability. The metamaterial models we discussed are usually equivalent double-negative or single-negative. So the term of"equivalent"should be emphasized in the theoretical analysis of metamaterials.This thesis mainly focuses on the research of properties of different equivalent metamaterial models. It involves complex models proposed in recent years, such as equivalent isotropy metamaterials, equivalent single-negative materials, equivalent anisotropy metamaterials and equivalent nonlinear metamaterials, so as to indicate the metamaterials'physical essence. To simplify the complex frame of the double open-loop resonators, single triangular open-loop resonators and symmetric triangular open-loop resonators are proposed. The author's work mainly consists of:(1) The present research status on metamaterials around the world and analysis of the theoretical and experimental basis of metamaterials are introduced. Comparing with the traditional material, detail description about the wave reflection and transmission in some equivalent isotropy metamaterial models are made. The results indicate that metamaterials represent lots of particular propagated properties, and the significance is to be seen by deep research.(2) The properties of surface waves along the equivalent single-negative slab waveguide are analyzed. According to the eigen mode equations, the graphical-solution technique is used in order to get dispersion curves profiles and energy fluxes distribution profile of odd and even symmetric TE surface modes which propagate along the epsilon-negative slab. It is found that surface waves propagate along the single-negative slab more slower than that along the traditional slab waveguide; Field and energy is confined on the top and bottom surfaces; Energy fluxes of odd and even symmetric surface waves have the opposite directions in a certain frequency range. This slow wave property may be utilized to design novel compact RF/microwave devices. Propagation matrices method is used to analyze the wave propagation properties in a pair of equivalent single negative slabs. Phenomena of bandpass, zero reflection and complete tunneling without any phase delay perform at some incident angles. Simulation results validate the salient features of such paired slabs.(3) The conditions that the negative refraction takes place when a plane wave passes from an equivalent isotropic right-handed material into another equivalent anisotropic metamaterial are presented in order to study the negative refraction of anisotropic metamaterials constituted by the practicable composite meta-materials. The conditions of the existence and the sign of the Goos-H(a|¨)nchen shift on this interface are also discussed. Simulation results are presented and used to prove the validities of the theoretical analysis.(4) Quadratic nonlinear phenomena in equivalent nonlinear metamaterials are detailedly analyzed. General coupled-mode equations for quadratic coupling in nonlinear metamaterials are studied. It is found that energy flow directions and energy spatial distributions are absolutely different in nonlinear metamaterials and in nonlinear traditional materials. It is shown that through a parametric amplification process, bigger output power of signal wave and idle wave can be obtained in a metamaterial slab than a traditional slab of the same thickness. The frequency range and energy fluxes'direction of surface waves on the interface of equivalent nonlinear metamaterials are dependent on the parameters of traditional materials, and their relations are analyzed by the graphical method.(5) Aiming at the complex frame of the double open-loop resonators, a simplified single triangular open-loop resonator is proposed, for simultaneously negative permittivity and negative permeability can be achieved by a single open-loop. Two kinds of symmetric triangular open-loop resonator combinations are designed. Parameter retrieval algorithms, refraction lens simulations and power transmission experiments are employed to validate the negative properties of these structures. The results are in well agreements.
Keywords/Search Tags:equivalent metamaterials, single-negative metamaterials, uniaxial anisotropy, surface-wave, Goos-Hanchenshift, quadratic nonlinearity, parametric amplification, triangular open-loop resonators, parameter retrieval
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