LAB1 - ELEC381 Pulse Reflections on Transmission Lines...

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ELEC381 Pulse Reflections on Transmission Lines Experiment Report Department: FST Major: EEE Name: CHEONG CHONG LAM (DA927981) TENG CHENG (DA928240)
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28/09/2011 Objective For this experiment, we need to verify the transmission line principles and the basic properties of transmission line in transient condition, also we need to find the inverse of TDR technique, and last we are going to demonstrate some reflection properties with different load terminations. Equipment 1. Function generator(assume that it is 50Ω system) 2. Digital oscilloscope 3. 2 BNC-to-BNC cables – 1 short-length 50-Ω (< 2 m) and 1 random length (with Label A,B, C, etc., > 10 meters long) with BNC connector on one end 4. 2 BNC TEE connectors + 1 BNC open connector for load 5. LCR 318 meter (share among different groups) 6. 50 ohm load termination with BNC connector 7. Assorted passive ckt. Elements (such as resistors, capacitors, and inductors) 8. Long Rulers (or equivalent via Engineering Sense, etc.) Producer of experiment and data analysis Connect the Function generator output to the oscilloscope input with the short 50-Ω coaxial cable (Figure 1). Use a BNC tee connector at the oscilloscope and use it to connect a 50 ohm load, so that the pulse generator output is properly terminated as shown below. Fig1. Connection of part 1 Adjust the pulse generator to produce pulses (zero offset), amplitude approximately 0.5 to 2 volt, pulse width approximately 10 ns to 150 nsec (or the shortest pulse width you can get from your function generator by adjusting the duty cycle or/and pulse width directly), and setting the frequency so that the scope can
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After the experiment, the observation of the oscilloscope and the data table are shown as follow: Fig1.1 Pulse wave form of part1 Waveform Amplitude(mV) Pulse width(ns) Frequency(Hz) Input voltage pulse 500 80 500K Terminal voltage pulse 494 80 500K Table the experiment data of part 1 As we can see that, the resistance of the short cable and the load are also 50Ω, so that there should be perfect match and didn’t have any reflection pulse, from calculation we can also see that the reflection factor, so there is also no any reflected wave. The transmission is no reflection. Furthermore we can calculated that V 1 - = Γ L V 1 + = 0; V(L,T) = V 1 + + V 1 - = V 1 + , so the calculation shows that the incident voltage should be same as the terminal voltage which should be 500mV . And the value of V T we measured is 494mV, so the error percentage is: E%=(500-494)/500*100%=1.2%, the error percentage is very small, so the result we get is accurate. 2. Pulse Signal w/o proper (matched) termination: Remove the 50 ohm load (as
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This note was uploaded on 02/27/2012 for the course ELEC 232 taught by Professor Terry during the Spring '12 term at University of Macau.

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LAB1 - ELEC381 Pulse Reflections on Transmission Lines...

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