antenna-theory.com

[ai.xuexi]

As we all know, we can transmit electrical signals use 2 wire transmission line system.
From the field view, we transmit TEM mode EM wave useing the 2 wire transmission line system.
However, the textbook analyze the situation of straightline transmission of the wave.
If we bend the 2 wire transmission line system, the signal propagate direction will also bend.
How can we analyze this situation use the Maxwell equations and boardary conditions? I have thought many years, and not get the answer.

and can we use the 2 wire transmission line system change the optical light propagate direction? the optical light can also be TEM mode.
Thanks in advance.

[bigSteve]

You can bend transmission lines of course and still get propagation. What ends up happening is that during the bend or transition, the relative geometry is changing compared to a flat section of transmission line.

As you can guess, this will alter the per unit series resistance, inductance, and shunt capacitance and conductance. The net result of this is as light change in the characteristic impedance of the transmission line. The severity of the bend will determine how much the characteristic impedance changes, and the length of the bend will affect the overall reflection or discontinuity of the line.

You can see more info on transmission lines here:
http://www.antenna-theory.com/tutorial/txline/transmissionline.php

For light waves, there is nothing special about them except the frequency is extraordinarily high so most structures are many wavelengths in dimension.

[ai.xuexi]

Thank you very much bigSteve.
so most structures are many wavelengths in dimension.
what does this mean?
can we use the 2 wire transmission line system change the signal propagate direction when structures are many wavelengths in dimension?

How can we analyze bend transmission lines useing the Maxwell equations and boardary conditions?

[ai.xuexi]

why wavelength so important?

[ai.xuexi]

can we use 2 wire transmission line to change the direction of light?

[bigSteve]

Your thinking is probably not very solid on this. Some notes:

1) the light you see is propagating (radiating) electromagnetic waves
2) The electric fields associated with a transmission line are bound waves, and so don't propagate much. So you wouldn't see the light move.

Also, to have a 2-wire transmission line that works at light frequencies the separation between the conductors would have to be nanometers

[ai.xuexi]