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信息科学与电子工程专业英语TechnicalEnglishForInformationScienceandElectronicEngineering信息科学与电子工程专业英语Unit3EMFields,AntennaandMicrowaves信息科学与电子工程专业英语PartIElectromagneticField3NewWordsvicinity邻近，附近stationary静止的，不变的charge电荷quantum量子photon光子oscillate振荡atom原子ultraviolet紫外线的catastrophe大灾难，大祸photoelectriceffect光电效应emission发射，散发metallic金属的incident入射的eject喷射，强制离开electrodynamics电动力学dynamics动力学gravitational重力的entity实体41Theelectromagneticfieldisaphysicalfieldproducedbyelectricallychargedobjects.Itaffectsthebehaviorofchargedobjectsinthevicinityofthefield.Theelectromagneticfieldextendsindefinitelythroughoutspaceanddescribestheelectromagneticinteraction.Itisoneofthefourfundamentalforcesinthenature(theothersaregravitation,theweakinteraction,andthestronginteraction)电磁场在空间无限延伸，并描述电磁相互作用。52Thefieldcanbeviewedasthecombinationofanelectricfieldandamagneticfield.Theelectricfieldisproducedbystationarycharges,andthemagneticfieldbymovingcharges(currents);thesetwoareoftendescribedasthesourcesofthefield.ThewayinwhichchargesandcurrentsinteractwiththeelectromagneticfieldisdescribedbyMaxwell’sequationsandtheLorentzforcelaw.电荷和电流与电磁场相互作用的方式由麦克斯韦方程组和洛伦兹力定律所描述。63Fromaclassicalpointofview,theelectromagneticfieldcanberegardedasasmooth,continuousfield,propagatedinawavelikemanner,whereasfromaquantummechanicalpointofview,thefieldcanbeviewedasbeingcomposedofphotons.从经典的角度，电磁场可认为是光滑、连续的场，以波动方式传播；而从量子力学的角度，场可看作是由光子组成的。74StructureoftheelectromagneticfieldTheelectromagneticfieldmaybeviewedintwodistinctways.Continuousstructure:Classically,electricandmagneticfieldsarethoughtofasbeingproducedbysmoothmotionsofchargedobjects.Forexample,oscillatingchargesproduceelectricandmagneticfieldsthatmaybeviewedina“smooth”,continuous,wavelikemanner.例如，振荡电荷产生电场和磁场，可看成平滑的、连续的波动方式。85Inthiscase,energyisviewedasbeingtransferredcontinuouslythroughtheelectromagneticfieldbetweenanytwolocations.Forinstance,themetalatomsinaradiotransmitterappeartotransferenergycontinuously.Thisviewisusefultoacertainextent(radiationoflowfrequency),butproblemsarefoundathighfrequencies(seeultravioletcatastrophe).Thisproblemleadstoanotherview.Theultravioletcatastrophe,alsocalledtheRayleigh-Jeanscatastrophe,wasapredictionofearly20thcenturyclassicalphysicsthatanidealblackbodyatthermalequilibriumwillemitradiationwithinfinitepower.96Discretestructure:Theelectromagneticfieldmaybethoughtofinamore“coarse”way.Experimentsrevealthatelectromagneticenergytransferisbetterdescribedasbeingcarriedawayinphotonswithafixedfrequency.Planck’srelationlinkstheenergyEofaphotontoitsfrequencynthroughtheequation:E=hn普朗克的关系式将光子的能量E及其频率n通过下式联系起来106wherehisPlanck’sconstant,namedinhonorofMaxPlanck,andnisthefrequencyofthephoton.Forexample,inthephotoelectriceffect–theemissionofelectronsfrommetallicsurfacesbyelectromagneticradiation–itisfoundthatincreasingtheintensityoftheincidentradiationhasnoeffect,andthatonlythefrequencyoftheradiationisrelevantinejectingelectrons.1例如在光电效应中，即因电磁辐射而从金属表面发射电子的现象，我们发现增加入射辐射的强度并无影响，只有辐射频率与发射的电子有关。117Thisquantumpictureoftheelectromagneticfieldhasprovedverysuccessful,givingrisetoquantumelectrodynamics,aquantumfieldtheorydescribingtheinteractionofelectromagneticradiationwithchargedmatter.已经证明电磁场的量子描述是非常成功的，引出了量子电动力学，一种描述电磁辐射与带电物体之间的相互作用的量子场理论。128DynamicsoftheelectromagneticfieldInthepast,electricallychargedobjectswerethoughttoproducetwotypesoffieldassociatedwiththeirchargeproperty.Anelectricfieldisproducedwhenthechargeisstationarywithrespecttoanobservermeasuringthepropertiesofthechargeandamagneticfield(aswellasanelectricfield)isproducedwhenthechargemoves(creatinganelectriccurrent)withrespecttothisobserver.相对于测量电荷性质的观察者，电荷静止时产生电场，电荷运动（产生电流）时产生磁场（和电场）。138Overtime,itwasrealizedthattheelectricandmagneticfieldsarebetterthoughtofastwopartsofagreaterwhole–theelectromagneticfield.2随着时间的推移，人们认识到电场和磁场是电磁场这一整体的两个部分。149Oncethiselectromagneticfieldhasbeenproducedfromagivenchargedistribution,otherchargedobjectsinthisfieldwillexperienceaforce(inasimilarwaythatplanetsexperienceaforceinthegravitationalfieldoftheSun).Iftheseotherchargesandcurrentsarecomparableinsizetothesourcesproducingtheaboveelectromagneticfield,thenanewnetelectromagneticfieldwillbeproduced.3电磁场中其它带电体就会受到一个力的作用如果另外这些电荷和电流的大小与产生上述电磁场的源是可比的，那么将产生一个新的净电磁场。159Thus,theelectromagneticfieldmaybeviewedasadynamicentitythatcausesotherchargesandcurrentstomove,andwhichisalsoaffectedbythem.TheseinteractionsaredescribedbyMaxwell’sequationsandtheLorentzforcelaw.电磁场可以认为是一个动力学实体，它促使其它电荷和电流运动，同时又受它们影响。信息科学与电子工程专业英语PartIIMicrostripAntenna17NewWordsmicrostripantenna微带天线patch片fabricate制造etch蚀刻insulate绝缘dielectric介电的，电介质substrate基底rectangular矩形的elliptical椭圆的eschew避开spacer定位架子robust牢固，稳健profile轮廓，姿态conformable适合的，顺从的UHF(ultra-highfrequency)特高频dBi(decibelisotropic)全向性分贝resonant谐振的lithographic平板印刷的transmissionline传输线fringe加边饰，条纹18NewWordsimpedance阻抗cavity空腔polarization极化，偏振diversity多样，差异性asymmetric非对称的virtualshortingplane虚拟短路平面191Intelecommunication,thereareseveraltypesofmicrostripantennas(alsoknownasprintedantennas)themostcommonofwhichisthemicrostrippatchantennaorpatchantenna.Apatchantenn