Field phases in quasi TEM

[supernano]

In quasi TEM transmission, waves in the two dielectrics try to travel at different velocities, does this mean that if the TL is long enough, you can have opposite phase in the fields within one dielectric and the other? If so, does this have impedance implications? (e.g. will the impedance be different at different points in the TL?)

From a previous post, there was a related comment: "Another thing about Quasi-TEM mode is that althought the actual wave propogates in 2 different medias in a hybrid (mixed) mode, an approximate static solution is used and an effective dielec. const. (εeff) and propogation const. is calculated." What I'm guessing from this is that there must be a boundary condition at the dielectric interface that forces the wave to travel at the same velocity in both mediums, close to the boundary... Is this correct?

 

[PlanarMetamaterials]

In quasi TEM transmission, waves in the two dielectrics try to travel at different velocities, does this mean that if the TL is long enough, you can have opposite phase in the fields within one dielectric and the other?

I don't believe so. Regardless of how badly the TEM approximation is applied, the mode in question still has a single propagation constant attributed to it. All of the fields propagate with this constant. So, I think the fields should stay within the same amount of phase along the line.