June 24, 2007
June 24, 2007
June 27, 2007
Electrical and Computer
12.567.1 - 12.567.18
Easy-to-Do Transmission Line Demonstrations of Sinusoidal Standing Waves and Transient Pulse Reflections Abstract
Junior, senior, and graduate level courses in electromagnetics often cover issues related to sinusoidal standing waves and transient pulses on transmission lines. This information is important for students because a theoretical understanding of such phenomena provides a concrete foundation for later study involving the general propagation of electromagnetic fields, and because transmission lines are critical in many different engineering applications. Unfortunately, however, the somewhat tedious mathematics underlying transmission line theory can cause students to snooze through lectures. This paper describes a simple set of classroom demonstrations that can enliven student interest in this important area. The phenomena demonstrated include:
• Time domain separation of input and output for the forward versus the return conductor. • The lossless or almost lossless character of the signal transfer through the transmission line. • Signal reflections and transmission line matching. • Time domain reflectometry applications, including characteristic impedance tests, terminating impedance tests, and losses.
The demonstrations discussed in this paper, which can be done using either two 2- channel or one 4-channel oscilloscope, are based on both sinusoidal and pulse excitations. Our experience has been that students become very enthusiastic as they clearly see the various types of standing wave patterns that are actively associated with different load and source impedances, and the various phenomena associated with transient pulse reflections.
Transmission lines first gained use in the mid-1800s to transfer Morse code over long distances. By the early 1900s, transmission lines had become an important means of transferring energy. Most recently, transmission lines have become inseparable components of high-speed electronic circuits and systems. Nowadays, typical applications of the transmission lines include:
• High voltage transmission lines • Telephone lines • Audio and TV cables, TV antenna cables • Computer network lines • Printed Circuit Board (PCB) connecting paths and interconnecting cables • Automotive control system interconnecting cables • Microwave communication systems, radars, etc.
Rusek, A., & Oakley, B. (2007, June), Easy To Do Transmission Line Demonstrations Of Sinusoidal Standing Waves And Transient Pulse Reflections Paper presented at 2007 Annual Conference & Exposition, Honolulu, Hawaii. 10.18260/1-2--1600
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