Circular polarized antennas are often used in ham radio especially to communicate with satellites[1].

I'm not expert enough to know, is this the same physics as what the article is talking about?

[1] https://www.qsl.net/sv1bsx/antenna-pol/polarization.html

Yes, see https://en.wikipedia.org/wiki/Orbital_angular_momentum_multi...

I believe the answer is yes. I recall something a few years ago where they modified a dish antenna to create a form of spiral signal. Multiple variations could be used at the same base frequency.