微波工程基础.docx

1. TE, TM, TEMTEM (transverse electromagnetic wave)Electric field and magnetic field are both perpendicular to direction of propagationTE (transverse electric)Electric field is perpendicular to direction of propagationTM (transverse magnetic)Magnetic field is perpendicular to direction of propagation2. Resistance 1.) Theelectrical resistanceof anelectrical conductoris the opposition to the passage of anelectric currentthrough that conductor; the inverse quantity iselectrical conductance.2.) Reactanceis the opposition of a circuit element to a change ofelectric currentorvoltage, due to that elementsinductanceorcapacitance.3.) Electrical impedanceis the measure of the opposition that acircuitpresents to acurrentwhen avoltageis applied. Which is a complex, real part is electrical resistance, and complex part is reactance. 3. Classification of transmission lineTEM transmission line : two-conductor line, coaxial lineTE, TM transmission line : rectangular waveguide, circular waveguideSurface wave transmission line : millimeter wave4.1.) Electrical length: , is the length of the transmission line, is the wave length of the wave working on the line.2.) Long-line: 3.) Distributed capacitance : , distributed inductance : , this is according to two-conductor line4.) There are always incident wave and reflected wave on a same transmission line. V+, I+ is the incident wave, and V-, I- is the reflected wave, thus we can get Reflectance: = V-/V+, = I-/I+.5.) Input impedance : Characteristic impedance: Reflectance: Load reflectance: Normalized impedance: , = 0, no reflected wave, the transmission line working in the matching status.5. Smith chart1.) Normalized impedance 2.) Resistance circle3.) Reactance circle4.) Electrical impedanc