Changing loop inductance based on frequency?
In the Return Current lecture (lesson 9 of Single-ended Transmission Lines & Signal Behavior), Eric shows how if you make a transmission line that follows the path of a rectangle, and place different frequencies on it, as you get to higher frequencies the return current follows the path of the outgoing signal.
I get that this is due to the path of least inductance being along the same path, as we learned about when considering partial mutual-inductance. However, doesn't this also mean that the inductance of the transmission line changes depending on frequency? At lower frequencies, you can't assume that the flux from the return current reduces the inductance of the outgoing signal, and vice versa. Whereas so far we've always considered transmission lines to have return paths that directly follow the outgoing path.
So, does this happen? If you have a transmission line that isn't perfectly straight, does the inductance - and therefore presumably the characteristic impedence - depend on frequency?
Wonderful, thanks everyone :)