Transcript Slide 1
Transmission Line and Termination Transmission Line Analysis • Wavelength Versus Distance – Lumped: L L – Distributed: • Pulse Transition Versus Propagation Delay • Single Mode – – – – Frequency response Propagation (timing and phase) delay Loss and dispersion Pulse distortion • Multimode – Modal analysis • Multi Lines – Crosstalk – Interference • Metallic Transmission Lines – Parallel Wire Pair • FM and TV antenna – Twisted Wire Pair • Phone line • 10BaseT Ethernet • http://www.swhowto.com /CAT5_Ch1.htm – Coaxial Cable • RG58 – Metallic Conduit – Planar Striplines • Printed circuit board • Hybrid IC carrier • Dielectric – Fiber • Glass • Polymer Characteristic Impedance • Impedance – Z=V/I for an infinite cable • Coaxial Cable – CATV, lab, microwave instrumentation 20 ln(D / d ) C 0 ln(D / d ) 2 R jL L 138 Z0 log(D / d ) G jC C L Vp 1 LC – Loss • Frequency dependent • Skin depth http://www.ipm.virginia.edu/p rocess/PVD/Pubs/thesis4/ chapter2.pdf – TEM mode – Unbalanced Skin Depth In Copper 9 Skin Depth, microns f 10 8 7 6 5 4 3 2 1 0 0.E+00 1.E+09 2.E+09 3.E+09 4.E+09 Frequency, Hz 5.E+09 6.E+09 Coaxial Cables Coax Attenuation in db per 100 feet (On 27MHz) Velocity Factor Description RG-8 1.15 dB .66 50 Ohm coax RG-59 2.0 dB .66 75 Ohm coax RG-8/U Foam 0.85 dB .80 50 Ohm coax, Foam Dielectric RG-59/U Foam 1.5 dB .79 75 Ohm coax, Foam Dielectric Belden 9913 0.7 dB .84 Premium 50 Ohm coax 1/2" Hardline 0.35 dB .81 Special coax, expensive! 1.2 dB .78 Small 50 Ohm coax. Preferred over RG-58. Recommended for mobile installations. RG-58 2.35 dB .66 50 Ohm coax RG-213 1.35 dB .66 50 Ohm coax. RG-11/U Foam 0.85 dB .80 75 Ohm coax. RG-11/U 1.35 dB .66 75 Ohm coax RG-8X (Mini-8) http://www.rfcafe.com/references/electrical/coax_chart.htm Coax Connectors • • • • • BNC Type N SMA APC7 K Coax Connectors Twin Lead Cable • Balanced – 300 Z0 276log(D / r) • Balun – Balanced to unbalance transformer Twisted Wire Pair • Network Cables – Cat 3, 4, 5, 5E, 6, .. – DSL wiring at home • http://www.smellyeyeball.com/dsl/ Striplines • Micro Stripline • Embedded Stripline • Coplanar Stripline • Loss – Metallic • Skin depth • Localized current flow – Dielectric • Loss tangent ' j ' ' Tan – Surface roughness '' ' Transmission Line Termination • Impedance Matching – Termination • Mismatch – Reflection • Time Domain Picture – http://www.williamson-labs.com/xmission.htm • Frequency Domain Analysis Reflection and Transmission • Reflection • Standing Wave Ratio • Wave Visualization – http://www.educatorscorner.com/index.cgi?CONTENT_ID=2 483 Impedance Matching • Effective Impedance – – – – – Load impedance Cable in front of load Frequency dependent Bandwidth Smith chart • http://www.educatorscorner.com/index.cgi?CONTENT_ID=2482 • Impedance Matching – Transformer • www.minicircuits.com/pages/pdfs/tran14-2.pdf – Stub • http://www.ee.surrey.ac.uk/Personal/D.Jefferies/stubs.html • Application – http://www.sss-mag.com/pdf/arrl_circles.pdf Time Domain Reflectometry • Principle – – – – Launch a pulse or a step waveform into the cable Monitor reflected signal Delay: location of mismatch Magnitude: amount of mismatch • Equipment – http://www.tek.com/Measurement/App_Notes/55_14601/en g/55W_14601_1.pdf – Pulse generator Time Domain Reflectometry • Measurements – http://bwrc.eecs.berkeley.edu/Classes/EE290C_S 04/lectures/Lect03_measurement.pdf – http://literature.agilent.com/litweb/pdf/59886505EN.pdf • Build Your Own TDR – http://www.web-ee.com/Schematics/TDR/tdr.htm Analysis for Digital Pulse • Pulse Analysis – http://www.mwrf.com/Articles/Print.cfm?ArticleID=5433 • Pulse Distortion • EESoft Modeling http://eesof.tm.agilent.com/pdf/asia_forum_2004_07. pdf Reading and Exercise • Reading – http://cktse.eie.polyu.edu.hk/eie403/Trans missionline.pdf • Exercise – http://courses.ece.uiuc.edu/ece450/Home work/HW3_F2004.pdf • Reference – http://www.connectorwizard.com/reference /articles/pdfs/GoldenStandard_Part2.pdf Chapter Review • Transmission Lines – balanced and unbalance – Balum • • • • • • Characteristic Impedance Reflection Coefficient Voltage Standing Wave Ratio Smith Chart Impedance Matching Time Domain Reflectometry