I've seen this video: https://www.youtube.com/watch?v=JjGep0W8ZHI,
There it is explained that an electromagnetic (here radio) wave has a phase shift if it was radiated in horizontal polarization, but it does not experience the phase shift when it was emitted vertically polarized when it gets reflected on the ground.
When reading up on phase shifts I didn't find anything in connection with polarization. But, I found that light will ALWAYS get reflected with a 180 degree phase shift when reflected on a denser medium. Therefore I am confused now, and don't understand if it is polarization dependent or not, and most importantly why?