Experiment 4 3d6u4i

Experiment 4 – Transmission Line Demonstrator This document contains the pre-lab questions that you need to answer in a sheet (1 per group) before you start the experiment. It also contains the main steps in the experiment, or more importantly, the data that you need to take for your lab report. Details of how to take that data can be found in the lab manual (attached) with respect to this experiment. Pre-Lab questions: (Answer each question in 2-3 sentences) i. What is the use of Transmission Line Demonstrator (TLD 511)? ii. What is the difference between Attenuation and Dispersion of a signal? iii. What is the difference between a travelling wave and a standing wave? How are standing waves produced?

Main steps in the experiment: i. ii. iii. iv.

v. vi. vii. viii. ix.

Various kinds of propagating pulses need to be demonstrated. First, using TLD 511, demonstrate step pulse of given width propagating forward as well as backward. Then propagate a sine wave on TLD 511, at different frequencies and measure the wavelength using the “Hold” button. With the previously obtained sine wave, gradually increase the attenuation control and observe the changes. Also, study the effect of change in frequency on this attenuation. To study dispersion, change the wave to step input, and set some mid-range attenuation. Observe the changes as compared to previous case. Similarly observe backward attenuation, by reversing the roles of both ends. Observe the wave signals (“step input”) for three terminations: Matched load, open circuit and short circuit cases. Comment upon your expectations versus results obtained. Observe the phenomenon of Superposition by sending step input pulses from both sides, as well as by superposing the incident and reflected waves on each other. Observe the standing wave pattern for different frequencies, for both open circuit and short circuit terminations. Comment upon the position of nodes and anti-nodes. Terminate the line with a mismatched load, and notice the partial reflection of incident wave and formation of standing waves. Experimentally, prove that the standing wave is the sum of incident and reflected wave. You are required to take snapshots of the wave from the transmission line demonstrator as experimental data and show them in the report.