'Skew planar wheel' antennas are popular for uhf. They are often described as circularly polarised, but I don't see how they would be. Are they instead just a mixed polarisation omnidirectional antenna ?

enter image description here

If they are circularly polarised, where would the equivalent 90 degree phase shift come from, as used in a normal circularly polarised antenna.

This account of testing this antenna indicated strong circular polarisation:

The results showed that this Skew-Planar is strongly right-hand circularly polarized, as expected. At my end, Clare's signal was S8 with his right-hand helix, and dropped to S1 when he switched to his left-hand helix.


Practical designs discussed here, also noteworthy is that the polarization is apparently determined by the direction of lean(skew?) of the four elements : http://www.slvrc.org/902band/skewplanar.htm

  • \$\begingroup\$ Hi and welcome! Please can you paste in a picture or diagram of one of these antennas, to get us started? \$\endgroup\$
    – tomnexus
    Commented Nov 29, 2016 at 17:57
  • \$\begingroup\$ Updated with an image \$\endgroup\$ Commented Nov 29, 2016 at 17:59
  • \$\begingroup\$ Hmm. If we only had two "blades" instead of four, and if each one emits in a dipole pattern (like any loop antenna,) then we actually have two vertical dipole antennas with a 1/2lambda separation, with a 90deg twist. In a horizontal line through the two, we'd expect pure circ-polarized emission. Cool! Two "propellors" with opposite screw, they can't hear each other! \$\endgroup\$
    – wbeaty
    Commented Dec 2, 2016 at 4:59
  • \$\begingroup\$ @wbeaty I don't follow. Where is the 90 degree phase difference coming from between the elements? \$\endgroup\$ Commented Dec 4, 2016 at 23:39

1 Answer 1


Figure 10 of this excellent explanation boils down to this:

If you ignore all the currents that cancel each other out due to symmetry, you can physically guide (via the copper) three currents Ez of similar magnitude and phase in the z-direction and one equivalent current in the y-direction, the resulting two equal and orthogonal currents being spaced a quarter wavelength apart.

So, with currents of equal magnitude and phase, orthogonal and spaced a quarter wavelength apart - voila, circular polarization!

Planar Wheel Antenna Primary Currents

  • \$\begingroup\$ Interesting, I've added a link to slvrc.org/902band/skewplanar.htm with practical designs. While I follow both of the ways you describe, I can't reconcile that with what I see on that site - apparently symmetrical designs - there doesn't appear to be a transmission line different, and with consistent element lengths? Also noteworthy is that the polarization direction appear to be determined by the lean or 'skew' of the elements themselves, this I still do not understand! \$\endgroup\$ Commented Dec 17, 2016 at 1:02
  • 1
    \$\begingroup\$ Agreed. I watched your reference & then dug further for a good explanation that considers the perfect symmetry, then edited my response. Pretty cool once you see Figure 10! \$\endgroup\$
    – neonzeon
    Commented Dec 17, 2016 at 13:38
  • \$\begingroup\$ Thanks, I think that explanation is as good as it's going to get, although it is still challenging to 'visualize' coherently. The explanation highlights a need for symmetry, what is interesting is that 3 and 5 lobe designs are being sold. Also some that are not curved but with straight lobes. It's hard to see how these would work well or be beneficial. A good gallery is at maxmyrange.com/assumptions.html \$\endgroup\$ Commented Feb 20, 2017 at 10:40

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.