# Multiple transmission lines

• likephysics

#### likephysics

If a source which has internal impedance 20 ohms is connected to multiple transmission lines of impedance somewhat equal to 20 ohms, which vary in length(maybe from 1" thru 8").
How do I analyze the reflections/draw the bounce diagrams.
According to a patent - http://www.docstoc.com/docs/5001518...rocessing-System---Patent-5696667#viewer-area
this is supposed to work. How? I can't figure out.

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Assuming you know the velocity factor of the lines, you could send a very short pulse and observe the returning pulse. You could then calculate the length of the line from the speed, if this is what you wanted to do.

If your signal source was continuous, then the returning pulse would interact with the later incoming waves and may form a standing wave if the line was resonant.

If you had multiple lines all connected in parallel and a continuous source, the result would be a mess of signals. A single pulse would give multiple reflections, but you would not know which of the parallel lines was responsible for each pulse.

What do you think that patent was describing? My copy of it had no diagrams, so it was difficult to see what was being described.

To paraphrase, the patent says, the multiple lines make the tx line like a lumped capacitor and inductor.
I don't understand how this happens.