A more fundamental explanation of reflections on transmission lines

Jan 15, 2009 2 Replies
E

Hi.



I know that reflections occur on a transmission line where there is an impedance discontinuity and I can show by reduction ad absurdum that an reflection must occur since we cannot have both V_1 = V_2 and I_1 = I_2 since I_1 = V_1/Z_1 and I_2 = V_2/Z_2. I can also grasp the concept in terms of a traveling wave on a piece of string/wire with a mass discontinuity.



What I cannot seem to understand is a more fundamental explanation of the phenomenon in electronic. By that I mean on an atomic/sub-atomic level. Can anyone provide such an explanation or point to relevant litterature?



Thanks in advance.


Vote
Twitter Facebook LinkedIn
B

an

How about water analogy... can you understand water wave reflection in terms of water molecules? Or acoustic reflections in terms of air molecules? Probably not. The 'wave' is not the 'transmission medium,' and if you zoom in your viewpoint, you'll no longer see the wave, but only see the medium.

Vote
Twitter Facebook LinkedIn
W

It's about the fields. The reason charges move along the wire, is an electric field pulls them. And, the result of moving charge is a magnetic field.

So, in addition to electrons (subatomic particles), there is some electric and magnetic field in the transmission line, and THAT is why the reflections occur: the fields hold energy, and the movement of that energy is disturbed by variations in the transmission medium, in ways that are consistant with wave reflection in other models (slinky/rope/string transverse acoustic waves, water/rubber tube pressure waves, and light/refractive media).

Vote
Twitter Facebook LinkedIn

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required