hi all. can circular polarization occurs in conformal antennas?... if yes.... then how axial-ratio is taken in conformal antennas.and how we can know with the help of current distribution whether such antennas are either right-hand circular polarized or left-hand circularly polarized
Well, your title question and what you're describing in your last question are two different things. If you want to know how to MEASURE axial ratio, that's easy and I'll simply point you to this previous question of how to measure axial ratio.
https://www.researchgate.net/post/How_do_I_measure_axial_ratio_of_the_antenna
However, if you're talking about current distributions, then you're generally talking about modeling and I don't bother with those questions as that's between you and your modeling tool vendor as to how to use their tool to do what you want! =)
In answer to your middle question, ANY antenna that is not a simple and symmetrical design (e.g. a dipole or a horn, etc.) is likely to have some cross polarization component that can cause some level of ellipticity. Even nicely linear antennas like horns become asymmetrical off-axis and thus have elliptical polarization components in those directions.
As for simple rules of thumb to evaluate your designs, if a current has to turn a corner, without a symmetrical component canceling it out on the opposite direction, then you can expect to have two orthogonal radiating components that are out of phase, and thus you get ellipticity. Likewise, a linear source signal that radiates and reflects off of components of the antenna or support structure such that the reflection changes polarization relative to the source (think reflector at an angle) then you'll end up with co -and cross-pol components from the direct and reflected signal that are out of phase and thus again, elliptical signals.
Note that I'm saying elliptical. Every signal is elliptical with a minor component between zero (linear) and 1x the major component (circular).
Hope that helps.
Michael
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