The obvious "turnstile patch" aside, here is something totally new to think about, RHCP at the left and LHCP at the right, no confusion intended:
I bought a couple of each and tested them for ellipticity and matching. They perform very well for such seemingingly simple radiatiors. Several could also be easily configured in a phased array or just use one for illuminating a prime focus dish of suitable f/D.
I am still at odds on how the current and phase distributions appear as a function of time (propaging wave), but they actually do work.
And pretty well at that. Most low cost patches on the market suffer from production repeatability issues.
It seems to me that this patch design is actually a kind of travelling wave antenna and somewhat like a flat/short helix. You can even determine the polarization handedness (chirality) from the path feedpoint.
Amazing things. As I do cannot afford a 3D electromagnetics simulator, this patch design makes me want to attempt scaling to 70 cm and make some field probe measurements with my VNA homebrew optical transducer