自动化与电气工程英文资料与中文翻译论文

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1、自动化与电气工程英文资料与中文翻译毕业论文1.1ANTENNASAnantennacanbedefinedasanelectricalconductororsystemofconductorsusedeitherforradiatingelectromagneticenergyorforcollectingelectromagneticenergy.Fortransmissionofasignal,radio-frequencyelectricalenergyfromthetransmitterisconverte

2、dintoelectromagneticenergybytheantennaandradiatedintothesurroundingenvironment(atmosphere,space,water).Forreceptionofasignal,electromagneticenergyimpingingontheantennaisconvertedintoradiofrequencyelectricalenergyandfedintothereceiver.RadiationPatternsAnantenna

3、willradiatepowerinalldirectionsbut,typically,doesnotperformequallywellinalldirections.Acommonwaytocharacterizetheperformanceofanantennaistheradiationpattern,whichisagraphicalrepresentationoftheradiationpropertiesofanantennaasafunctionofspacecoordinates.Thesimp

4、lestpatternisproducedbyanidealizedantennaknownastheisotropicantenna.Anisotropicantennaisapointinspacethatradiatespowerinalldirectionsequally.Theactualradiationpatternfortheisotropicantennaisaspherewiththeantennaatthecenter.However,radiationpatternsarealmostalw

5、aysdepictedasatwo-dimensionalcrosssectionofthethree-dimensionalpattern.ThepatternfortheisotropicantennaisshowninFigure1.1a.Thedistancefromtheantennatoeachpointontheradiationpatternisproportionaltothepowerradiatedfromtheantennainthatdirection.Fogure1.1bshowsthe

6、radiationpatternofanotheridealizedantenna.Thisisadirectionalantennainwhichthepreferreddirectionofradiationisalongoneaxis.Theactualsizeofaradiationpatternisarbitrary.WhatisImportantistherelativedistancefromtheantennapositionineachdirection.Therelativedistancede

7、terminestherelativepower.TodeterminetherelativepowerInagivendirection,alineisdrawnfromtheantennapositionattheappropriateangle,andthepointofinterceptwiththeradiationpatternisdetermined.Figure1.1showsacomparisonoftwotransmissionangles,AandB,drawnonthetworadiatio

8、npatterns.heisotropicantennaproducesanomnidirectionalradiationpatternofequalstrengthinalldirections,sotheAandBvectorsareofequallength.FortheantennapatternofFigure1.1b,theBvectorisl