MetaMaterials[共15页]

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2024-04-27 发布于云南
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METAMATERIALSCalebHughesHassanIsmailBrettMcCutchanECIV30311/30/2010Scope•WhatareMetamaterials•HowTheyWork•Types•Applications•RecentAdvancesWhatareMetamaterials?Engineered(attheatomiclevel)materialsthathaveuniquepropertiesnotfoundinnatureduetothearrangementanddesignoftheirconstituentsNOTE:THEPROPERTIESARETHATOFTHEENTIREARRANGEMENTANDNOTTHECONSTITUENTSTHEMSELVES“Meta”=above,superior,beyondSomeHistory•TheoreticaldesignbyVictorVeselagoin1968–Predictedmetamaterialsactinexactoppositemannerthannaturalmaterials(likenegativerefractiveindex)•Dr.JohnPendryshowedpracticalmethodofmakingmetamaterialsin1999V.G.VeselagoSirJohnPendryhttp://cobweb.ecn.purdue.edu/~ece695s/Lectures/Lecture_15.pdfHowDoesitWork?Normally,wavespropagateandinteractwithdifferentmediaaccordingtoSnell’sLawMetamaterials“Grab”wavesandsmoothlyredirectsthemduetonegativeindexofrefractionMaterialunitsmustbesmallrelativetothewavelengthbeingmanipulatedhttp://www.newscientist.com/blog/technology/labels/physics.htmlTypesofMetamaterials•Electromagnetic–Transversewaves•Acoustic–Longitudinalwaves•Seismic–TransverseandLongitudinalwavesElectromagneticMetamaterialsNegativeRefractiveIndexhttp://www.imagico.de/pov/metamaterials.htmlRefractiveindexElectricpermittivityMagneticpermeabilityElectromagneticMetamaterials•Antennas–Negativeindexofrefractionmeansmorewavebendingwhichmeanssmallerantenna(fewmm)http://www.metacloak.net/FractalMetamaterialMonopoleAntennaWhatWeDid.pdf―Candoublefrequencyrange―IncreaseradiatedpowerElectromagneticMetamaterials•Invisibility–VisiblelightwavesmustbemanipulatedCloakONCloakOFFhttp://cobweb.ecn.purdue.edu/~ece695s/Lectures/Lecture_16.pdfAcousticMetamaterials•Acousticwavesaredifferentthanelectromagneticwaves–LongitudinalwavesratherthanTransversewaves•Commonphysicalconceptsofwaves–Wavevector–Waveimpedence–Powerflow•NegativeRefractiveindex–NegativeMassDensity–NegativeBulkModulusRefractiveindexBulkModulusMassDensityAcousticMetamaterials•SoundproofRoom•InvisibleSubmarines(SonarBlocking)•SeismicMetamaterials-Negatethedestructiveeffectofseismicwavesonsurfacestructures-Requiresthedecouplingoflongitudinalpressurewavesandtransverseshearwaves,redirectingthemaroundacylindricalmetamaterialcloakCreationofMetamaterials•ContactPhotolithographyusedforlargernanomaterials•ElectronBeamLithographyusedforsmaller,moredetailedstructureshttp://www.memsnet.org/mems/processes/lithography.htmlhttp://en.wikipedia.org/wiki/File:Left-handed_metamaterial_array_configuration.jpgLimitations•Smallwavelengthsrequireverysmallunits•Mustbeabletohandlerangeofwavelengthsforsomeapplications–FrequencySelectiveSurfaces(FSSakaTunable)http://www.joeruff.com/artruff/physics/Light/emspec.gifFurtherReadingPurdueuniversity—Nanophotonics&MetamaterialsECE695shttp://cobweb.enc.purdue.edu/~ece695sD.R.SmithatDukeUniversity—http://people.ee.duke.edu/~drsmith/pubs_smith.htmQuestions?

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