Ch7-Microwave Passive Device

MicrowavePassiveDeviceMicrowavePassiveDeviceFoundationsofMicrowaveTechnologyFoundationsofMicrowaveTechnologyFebFeb--Jun/2010Jun/2010Dr.KunDr.KunXuXu（徐坤）（徐坤）Tel:+86Tel:[phone]E62282332E--mail:mail:[e-mail]@bupt.edu.cnKeyLabofInformationPhotonicsandOpticalCommunicationsKeyLabofInformationPhotonicsandOpticalCommunications(BeijingUniversity(BeijingUniversityofPostsandTelecommunications)ofPostsandTelecommunications),Ministry,MinistryofEducation,ofEducation,P.R.ChinaP.R.ChinaMicrowaveDevicesMicrowaveDevices微波系统＝微波传输线＋微波元器件（对信号进行处理和变换）微波元器件＝无源微波元件＋有源微波器件微波元器件：线性互易元件（阻抗匹配器（可调）、阻抗变换器（不可调）、衰减器、移相器、功分器、定向耦合器、滤波器、微波电桥等）＋线性非互易元件（线性各向异性介质：区别沿不同方向传输的导行电磁波。如：隔离器、环形器等）＋非线性元件与器件（微波信号的频率或频谱变换。如：调制器、检波器、混频器、倍频器等）＋有源器件（产生微波能量或对微波信号进行放大。如：振荡器、放大器、微波管等）PassiveDevicePassiveDeviceDESCRIPTIONAredesignedusingsectionsofcoaxialline,waveguides,andstriplinesandmicrostriplinesCanbeconsideredasone-portormultiportnetworksCharacterizedbyVSWR,reflectioncoefficient,andvariouslossesUsage:laboratory,microwavecommunication,radarsystemMostcommonlyused:linesections,connectors,terminators,adapters,attenuators,phaseshifters,isolators(circulators),directionalcouplers,powerdividers(T-junctions)andcombiners…ConnectorsandAdapters(ConnectorsandAdapters(适配器适配器))AttenuatorsAttenuatorsAttenuatorsarepassivedevicesusedtocontrolpowerlevelsinamicrowavesystembypartiallyabsorbingthetransmittedsignalwave.Bothfixedandvariableattenuatorsaredesignedusingresistivefilms.吸收式衰减器：镀有金属粉末的金属性介质片（电阻性材料－高损耗吸收材料，吸收微波功率），两端呈尖劈状；截止式衰减器：根据波导中截止电磁波场强沿传播方向按指数规律衰减，配合隔离器、环形器使用，抑止反射干扰；旋转偏振式衰减器：通过调整微波吸收介质片相对于电场的角度来改变衰减量。PhaseShiftersPhaseShiftersAphaseshifterisatwo-portpassivedevicethatproducesavariablechangeinphaseofthewavetransmittedthroughit.调整移相器的实际长度或改变行波在移相器内实际通过的距离；调整移相器内填充介质的物理参数或几何参数，如用低损耗、高介电常数的材料，通过改变其在移相器内体积和位置；调整波导宽边尺寸，传播常数与截止波长（宽边尺寸）相关。00ljljeeSPowerDividersandCombinersPowerDividersandCombinersApowerdividerisadevicetosplittheinputpowerintoanumberofsmalleramountsofpoweratmultipleports(N)tofeedNnumberofbranchingcircuitswithisolationbetweentheoutputports.Waveguideteesarethree-portcomponentsusedtoconnectabranchorsectionofthewaveguideinseriesorparallelwiththemainwaveguidetransmissionlineforprovidingmeansofsplitting,andalsoofcombiningpowerinawaveguidesystem.Directionalcouplersarefour-portpassivedevicesusedforcouplingaknownfractionofthemicrowavepowerstoaport(coupledport)intheauxiliarylinewhileflowingfrominputporttooutputportinthemainline.Theremainingportisideallyisolatedportandmatchedterminated.ThreeThree--PortNetworks(TPortNetworks(T--Junction)Junction)Thescatteringmatrixofanarbitrarythree-portnetworkhasnineindependentelements:111213212223313233SSSSSSSSSSDividerorcoupler1P21PP311PPDividerorcoupler2P3P123PPPThreeThree--PortNetworks(TPortNetworks(T--Junction)Junction)121312231323000SSSSSSS2212131SS2212231SS2213231SS*13230SS*23120SS*12130SS所有端口阻抗匹配：Sii=0各向同性媒质：互易矩阵－对称阵网络无损：能量守恒，么正特性Athree-portnetworkcannotbelossless,reciprocal,andmatchedalltheports.Ifanyoneofthesethreeconditionsisrelaxed,thenaphysicallyrealizabledeviceispossible.?ThreeThree--PortNetworks(Circulator)PortNetworks(Circulator)121321233132000SSSSSSS*31320SS*21230SS*12130SS2212131SS2221231SS2231321SS所有端口阻抗匹配：Sii=0各向异性媒质：非互易（非对称）矩阵网络无损：能量守恒，么正特性1223310SSS2132131SSS2132130SSS1223311SSS001100010S010001100SThreeThree--PortNetworks(TPortNetworks(T--Junction)Junction)*13230SS**121323330SSSS**231233130SSSS2212131SS2212231SS2221323331SSS两个端口阻抗匹配：S33≠0各向同性媒质：互易（对称）矩阵网络无损：能量守恒，么正特性02313SS＝2313SS＝13312SS＝3323132312131200SSSSSSSS023421223SSSFourFour--PortNetworks(DirectionalCouplers)PortNetworks(DirectionalCouplers)1213141223241323341424340000SSSSSSSSSSSSS****132314241413242300SSSSSSSS22*1413240SSS所有端口阻抗匹配：Sii=0各向同性媒质：互易矩阵－对称阵网络无损：能量守恒，么正特性**141234230SSSS2212131SS2212241SS2213341SS2224341SS1324SS1234SS02314SS＝DirectionalCouplers2413SS＝3412SS＝03414*2312*SSSSTwoDecoupledtwo-portnetworks(1&4,2&3)×n2FourFour--PortNetworks(DirectionalCouplers)PortNetworks(DirectionalCouplers)2212131SS2212241SS2213341SS2224341SS1324SS1234SS1234SS13jSe24jSe**121324340SSSS/200000000jjSjj0,00000000S221TheSymmetricalCouplerTheAntisymmetricalCouplerAnyreciprocal,lossless,matchedfour-portnetworkisadirectionalcoupler.DirectionalCouplersDirectionalCouplers13Coupling==10log20logPCdBP3414Directivity==10log20logPDdBPS1144Isolation==10log20logPISdBPIDC2213＝S00000000jjSjj222121－＝＝S01010010012010jjSjj011010011100120110SHybridCouplersHybridCouplers/200000000jjSjj0,00000000STheSymmetricalCouplerTheAntisymmetricalCoupler2/1＝Couplerfactoris3dB魔T混合接头或微带混合环二分支耦合器Fedatport1Fedatport4The180。HybridAsignalappliedtoport1willbeeve