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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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**Transmission line modeling**simulation with PSpice ASEE conference 2007**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.**Fig. 1b Low frequency sine-wave (1MHz), TL matched (50**ohms), observe small delays and almost identical amplitudes**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)**Fig. 2a Sine-wave of 17 MHz, matched load**The waves have the same amplitudes, the phases are different.**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).**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.**Fig. 4a Open ended TL, 3.5 MHz, observe minimum (input)**One quarter wave pattern is shown**Fig. 4b Open ended TL, 3.5 MHz, observe minimum (input)**One quarter wave pattern is shown**Fig. 4c Open ended TL, 3.5 MHz, observe minimum (input)**One quarter wave pattern is shown**Fig. 5 Open ended TL, 5.5 MHz, observe shift of the minimum**The minimum is located quarter wave from the end.**Fig. 7 Shorted TL, low frequency,1MHz applied, observe**zero output voltage**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).**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),**Fig.11 Shorted TL, 11 MHz, two minima, first shifted**towards the load, ¼ wavelength + ½ wavelength**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.**Fig. 13a Open ended TL, Input Pulse rise time = 240 ns,**Output = 120 ns, Long pulse applied, measurement circuit**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.**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.**Fig. 14a Open ended TL, long pulse applied, source matched,**measurement circuit.**Fig. 14b Open ended TL, long pulse applied, source**matched, simulations.**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.**Fig. 15c Open ended TL, short pulses applied to show**“radar effect”, circuit.**Fig. 15c Open ended TL, short pulses applied to show**“radar effect”. Echo is observed (Upper Channel – Input), doubled amplitude – Lower Channel, simulations.**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.**Fig 16b Shorted TL, narrow pulses, observe change of**polarity of a reflected pulse (Upper Channel – Input).**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).**Fig. 17a Transmission line and the inductive load, the**source resistance is matched (50 ohms), circuit.**Fig. 17b Transmission line and the inductive load, the**source resistance is matched (50 ohms), simulated waves.**Fig. 17c Transmission line and the inductive load, the**source resistance is matched (50 ohms), measurements.**Fig. 17d Transmission line and the inductive load, the**source resistance is matched (50 ohms), larger time scale**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).**Fig. 17f Transmission line and the capacitive load, the**source resistance is matched (50 ohms), circuit.**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.**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.**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.**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 .**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**Fig. 19a Reflection from the unmatched load of the TL**(Rload =27 ohms), source is matched, circuit.**Fig. 19b Reflection from the unmatched load of the TL**(Rload =27 ohms), source is matched, simulated waves.**Fig. 19c Reflection from the unmatched load of the TL**(Rload =27 ohms), source is matched, measured waves.**Fig. 20a Reflection from the unmatched load of the TL**(Rload =100 ohms), source is matched**Fig. 20c Reflection from the unmatched load of the TL**(Rload =100 ohms), source is matched**Fig. 21a Reflection from the unmatched load and the source**of the TL (Rsource = 25 ohms Rload =open circuit), circuit.**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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