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ECE 546 Lecture - 08 Lossy Transmission Lines

ECE 546 Lecture - 08 Lossy Transmission Lines. Spring 2014. Jose E. Schutt-Aine Electrical & Computer Engineering University of Illinois jesa@illinois.edu. Loss in Transmission Lines. Signal amplitude decreases with distance from the source. Skin Effect in Lines.

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ECE 546 Lecture - 08 Lossy Transmission Lines

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  1. ECE 546 Lecture - 08 Lossy Transmission Lines Spring 2014 Jose E. Schutt-Aine Electrical & Computer Engineering University of Illinois jesa@illinois.edu

  2. Loss in Transmission Lines Signal amplitude decreases with distance from the source.

  3. Skin Effect in Lines

  4. Skin Effect in Microstrip er H. A. Wheeler, "Formulas for the skin effect," Proc. IRE, vol. 30, pp. 412-424,1942

  5. Skin Effect in Microstrip Current density varies as Note that the phase of the current density varies as a function of y The voltage measured over a section of conductor of length D is:

  6. Skin Effect in Microstrip The skin effect impedance is is the bulk resistivity of the conductor where with  Skin effect has reactive (inductive) component

  7. Lossy Transmission Line Telegraphers Equation: Time Domain

  8. Lossy Transmission Line Telegraphers Equation: Frequency Domain

  9. Lossy Transmission Line forward wave backward wave

  10. l g Lossy Transmission Line

  11. Effects of Losses • Signal attenuation • Dispersion - Rise time degradation

  12. RC Transmission Line R : series resistance per unit length C : shunt capacitance per unit length For very high w,

  13. RC Transmission Line If then RT = Rl : total resistance CT = Cl : total capacitance

  14. RC Transmission Line Logic threshold Logic threshold

  15. Long Cable 100m Category-5 Cable

  16. Short Cable 1m Category-5 Cable

  17. Category 5 Cable Resistance and velocity

  18. Zovrovrs Rs p fmax (W) (m/ns) (m/ns-GHz) (W/m-GHzp) (GHz) Category 5 100 0.724 -0.165 15.38 0.482 0.2 24-Ga 100 0.678 1.157 29.03 0.593 0.1 Category 3 100 0.705 11.06 12.31 0.473 0.01 SMA 50 0.700 0.113 7.94 0.415 0.2 Cable Loss Model

  19. To simulate lossy TL with resistive loads No closed form solution Simplest method is to use IFFT Lossy TL Simulation 19

  20. Time-Domain Simulations

  21. Pulse Propagation (CAT-5)

  22. Pulse Propagation (MP/CM)

  23. Pulse Propagation (RG174)

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