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Transmission line modeling simulation with PSpice ASEE conference 2007

Transmission line modeling simulation with PSpice ASEE conference 2007. Transmission Lines Demonstration High Frequency Electronics Course EE527 Andrew Rusek Oakland University

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Transmission line modeling simulation with PSpice ASEE conference 2007

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  1. Transmission line modeling simulation with PSpice ASEE conference 2007

  2. Transmission Lines Demonstration High Frequency Electronics Course EE527 Andrew Rusek Oakland University Winter 2007 Demonstration is based on the materials collected from measurement set up to show sinusoidal and step responses of a transmission line with various terminations. Results of selected simulations are included.

  3. Fig.1a Test circuits

  4. Fig. 1b Low frequency sine-wave (1MHz), TL matched (50 ohms), observe small delays and almost identical amplitudes

  5. Fig. 1c Low frequency sine-wave (1MHz), TL matched (50 ohms) Channel 4 (output) shows the voltage for grounded center conductor and a probe input connected to the outer conductor (shield), observe the phase inversion of the last wave (180 degrees)

  6. Fig. 2a Sine-wave of 17 MHz, matched load The waves have the same amplitudes, the phases are different.

  7. Fig. 2b Sine-wave of 17 MHz, matched load Channel 4 (output) shows the voltage for grounded center conductor and a probe input connected to the outer conductor (shield).

  8. Fig. 3 Open ended TL, sine-wave of 1 MHz applied, observe 2X larger amplitude in comparison with previous tests, amplitudes are almost the same for all waves.

  9. Fig. 4a Open ended TL, 3.5 MHz, observe minimum (input) One quarter wave pattern is shown

  10. Fig. 4b Open ended TL, 3.5 MHz, observe minimum (input) One quarter wave pattern is shown

  11. Fig. 4c Open ended TL, 3.5 MHz, observe minimum (input) One quarter wave pattern is shown

  12. Fig. 5 Open ended TL, 5.5 MHz, observe shift of the minimum The minimum is located quarter wave from the end.

  13. Fig. 6 Open ended TL, 11 MHz, observe two minima

  14. Fig. 7 Shorted TL, low frequency,1MHz applied, observe zero output voltage

  15. Fig. 8 Shorted TL, 5 MHz applied

  16. Fig. 9 Shorted TL, 7 MHz, observe two minima (half wave). If the length of the line is known, the dielectric constant can be calculated (Lambda_cable/2 = 12m, open space Lambda = 42.8m).

  17. Fig. 10 Shorted TL, 7 MHz, increased vertical sensitivity; observe two minima as before and effects of stray inductance of the source and probe leads (half wave),

  18. Fig.11 Shorted TL, 11 MHz, two minima, first shifted towards the load, ¼ wavelength + ½ wavelength

  19. Fig. 12 Pulse response of open ended TL, slow pulse (0.3us rise time), no reflections observed, Channel 2 – Input, Channel 4 – Output, observe the delay.

  20. Fig. 13a Open ended TL, Input Pulse rise time = 240 ns, Output = 120 ns, Long pulse applied, measurement circuit

  21. Fig. 13b Open ended TL, Input Pulse rise time = 240 ns, Output = 120 ns, Why Output is faster than Input ? End of TL reflection adds to incident (Real rise time of the input wave is120 ns), and this effect doubles Input signal rise time. Long pulse applied, simulations.

  22. Fig. 13c Open ended TL, Input Pulse rise time = 240 ns, Output = 120 ns, Why Output is faster than Input ? End of TL reflection adds to incident (Real rise time of the input wave is120 ns), and this effect doubles Input signal rise time. Long pulse applied, measurements.

  23. Fig. 14a Open ended TL, long pulse applied, source matched, measurement circuit.

  24. Fig. 14b Open ended TL, long pulse applied, source matched, simulations.

  25. Fig. 14c Open ended TL, Input – Channel 2 shows incident step and reflected step (doubled TL delay), source matched, Output – Channel 4 shows doubled incident wave level, delayed (about 60 ns), long pulse applied. Distance between steps of Channel 2 – 2X TL delay time, measurements.

  26. Fig. 15c Open ended TL, short pulses applied to show “radar effect”, circuit.

  27. Fig. 15c Open ended TL, short pulses applied to show “radar effect”. Echo is observed (Upper Channel – Input), doubled amplitude – Lower Channel, simulations.

  28. Fig. 15c Open ended TL, short pulses applied to show “radar effect”. Echo is observed (Channel 2 – Input), doubled amplitude – Channel 4 – Output, observe effects of the losses of TL – echo is slower and smaller. Distance between pulses of Channel 2 – 2X TL delay time. Measured unit delay yields 20cm/ns.

  29. Fig 16a Shorted TL, narrow pulses, circuit.

  30. Fig 16b Shorted TL, narrow pulses, observe change of polarity of a reflected pulse (Upper Channel – Input).

  31. Fig 16c Shorted TL, narrow pulses, “short” is not really short at HF (Channel 4), observe change of polarity of reflected pulse (Channel 2 – Input).

  32. Fig. 17a Transmission line and the inductive load, the source resistance is matched (50 ohms), circuit.

  33. Fig. 17b Transmission line and the inductive load, the source resistance is matched (50 ohms), simulated waves.

  34. Fig. 17c Transmission line and the inductive load, the source resistance is matched (50 ohms), measurements.

  35. Fig. 17d Transmission line and the inductive load, the source resistance is matched (50 ohms), larger time scale

  36. Fig. 17e Transmission line and the inductive load, the source resistance is matched (50 ohms), display adjusted to calculate the time constant and inductance (L = 100 uH).

  37. Fig. 17f Transmission line and the capacitive load, the source resistance is matched (50 ohms), circuit.

  38. Fig. 17g Transmission line and the capacitive load, the source resistance is matched (50 ohms), display adjusted to calculate the time constant and capacitance (C = 10nF), simulated waves.

  39. Fig. 17h Transmission line and the capacitive load, the source resistance is matched (50 ohms), display adjusted to calculate the time constant and capacitance (C = 10nF), measured waves.

  40. Fig. 18 a. Matched TL, reversed connections of Output Probe (center conductor is grounded} – the waves show that outer conductor of TL also participates in signal delay, circuit.

  41. Fig. 18 b. Matched TL, reversed connections of Output Probe (center conductor is grounded} – the waves show that outer conductor of TL also participates in signal delay, simulated waves .

  42. Fig. 18 c. Matched TL, Input – Channel 2, reversed connections of Output Probe (center conductor is grounded} – Channel 4, shows that outer conductor of TL also participates in signal delay

  43. Fig. 19a Reflection from the unmatched load of the TL (Rload =27 ohms), source is matched, circuit.

  44. Fig. 19b Reflection from the unmatched load of the TL (Rload =27 ohms), source is matched, simulated waves.

  45. Fig. 19c Reflection from the unmatched load of the TL (Rload =27 ohms), source is matched, measured waves.

  46. Fig. 20a Reflection from the unmatched load of the TL (Rload =100 ohms), source is matched

  47. Fig. 20c Reflection from the unmatched load of the TL (Rload =100 ohms), source is matched

  48. Fig. 21a Reflection from the unmatched load and the source of the TL (Rsource = 25 ohms Rload =open circuit), circuit.

  49. Fig. 21b Reflection from the unmatched load and the source of the TL (Rsource = 25 ohms Rload =open circuit), simulated waves.

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