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1、1.TE,TM,TEMTEM(transverseelectromagneticwave)ElectricfieldandmagneticfieldarebothperpendiculartodirectionofpropagationTE(transverseelectric)ElectricfieldisperpendiculartodirectionofpropagationTM(transversemagnetic)Magneticfieldisperpendiculartodirectionofpropagation
2、2.Resistance1.)Theelectricalresistanceofanelectricalconductoristheoppositiontothepassageofanelectriccurrentthroughthatconductor;theinversequantityiselectricalconductance.2.)Reactanceistheoppositionofacircuitelementtoachangeofelectriccurrentorvoltage,duetothatelement
3、'sinductaneeorcapacitanee.3.)Electricalimpedanceisthemeasureoftheoppositionthatacircuitpresentstoacurrentwhenavoltageisapplied.Whichisacomplex,realpartiselectricalresistance，andcomplexpartisreactance.3.ClassificationoftransmissionlineTEMtransmissionline:two-conducto
4、rline,coaxiallineTE,TMtransmissionline:rectangularwaveguide,circularwaveguideSurfacewavetransmissionline:millimeterwave1.)Electricallength:7/2,1isthelengthofthetransmissionline,Aisthewavelengthofthewaveworkingontheline.2.)Long-line:7/2>0.13.)Distributedcapacitanee:C
5、=5pF/m,distributedinductanee:L=2pH/in,thisisaccordingtotwo-conductorline4.)Therearealwaysincidentwaveandreflectedwaveonasametransmissionline.V+,1+istheincidentwave,and卜isthereflectedwave,thuswecangetReflectanee:「=7_冬(1+门v-/v+,r=i-/i+.5.)Inputimpedance:《ri+rZc=Fz^ZcF
6、TCharacteristicimpedanee:.兰丄丄r=^cReflectance:乙+Z©Loadreflectanee:ZtNormalizedimpedanee:当Zp=Zc时，乙7^c,r=0,noreflectedwave,thetransmissionlineworkinginthematchingstatus.5.Smithchart1.)Normalizedimpedaneezl+r(2.4.1),z-lz+12.)Resistaneecirclefrf5.)Example路如图2.19所示。这种集总参数
7、与串联容抗的数值和位置。解本例题的圆图求解示意图如图2.20所示。由给定的Zf和Zc数值计算归一化负载阻抗ZF二0.217+yo.lo因为是串联电路，所以不必变换到导纳J圆图。在阻抗圆图上查到Zf=0.217+j0.1I（比）**（zc）n^i
8、=>(300-jy)Q图例题2—线长为0.81Z、特性阻抗为500的无耗线，负载阻抗为Zf=75_/25G，求其输入阻抗、输入导纳。解：①如图所示，先求岀归一化负载阻抗为zF=（75->25）/50=1.5->0.5在阻抗圆图上标出此负载点2尸，其对应的向电源波长数为0.296,如图所
9、示。②然后，以点为起点，沿等厂圆顺时针（向信源）旋转电长度0.81到Zj応,对应的向电源波长数为0.296+0.31=0.606=0.5+0.106（取0.106）,查得距负载0・81几处的输入阻抗为Z加=0・8+丿0・40.812.:1.Usingsmithcharttoc
