# How does signal circulate and travel across a transmission line?

1. ## How does signal circulate and travel across a transmission line?

Hello,

Assumed you have a tiny voltage source, from a sensor. (like 0.3V).
This source is connected to a 0.25mm copper jumper wire.
The second extremity is connected to a voltage meter.
All the way from source, to the volt-meter, how this signals travels? What are the physical laws?

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2. ## Re: How does signal circulate and travel across a transmission line?

Originally Posted by KhaledOsmani
Hello,

Assumed you have a tiny voltage source, from a sensor. (like 0.3V).
This source is connected to a 0.25mm copper jumper wire.
The second extremity is connected to a voltage meter.
All the way from source, to the volt-meter, how this signals travels? What are the physical laws?
Your question indicates that you have no basic knowledge of electronics principles.

First you fail in defining the signal source and the signal. A signal source must be specified by its impedance , and a signal has not only a voltage but a frequency spectrum.

Connecting lines may be designed as TEM or other types, and propagating signals travelling along do not only pass through the conductor(s) but in the dielectric medium.

Go and read the basics of electronics!

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3. ## Re: How does signal circulate and travel across a transmission line?

Sounds like you are describing a basic DC circuit that doesn't involve transmission line effects. Look for basic laws describing the circuit's behaviour http://en.wikipedia.org/wiki/Kirchhoff%27s_circuit_laws
http://en.wikipedia.org/wiki/Ohm%27s_law
http://www.ibiblio.org/kuphaldt/elec.../DC/index.html

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4. ## Re: How does signal circulate and travel across a transmission line?

A signal transmission needs TWO wires, not just one wire. The second wire is the return wire to form a complete loop.

5. ## Re: How does signal circulate and travel across a transmission line?

Yes Audioguru, that's what I ment, a twisted pair cable

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6. ## Re: How does signal circulate and travel across a transmission line?

With DC current, the electrons travel around the loop in one direction.
With AC current, the electrons alternate back and forth in the loop.

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