Circular Polarization
I've recently seen some amazing results with TurboWave antennas - turns out that they use CP. They appear to be excellent for penetration through foliage, concrete, or where multipath fading is a problem (where the polarization shifts because of a bounce off something, like water, or buildings).
In any event, I've never seen such performance (I have nothing to do with the company), and I wonder if anyone in SA has tried them.
... the slh16 is a mean mutha.
Points:
- CP --> non-CP means a maximum of 50% of the available signal can be utilized (but this is often much better than,say, 2 yagis, which fight the polarization fight all the time, mostly far below this)
- CP-->CP links are very stable, and 100% of the signal power can theoretically be used.
I would love to see 2 high slh16 antennas with 500mW boosters run a link between JHB and Pretoria.
pookfuzz--
Yes, circular polarization is ideal where signals might bounce off things. The type of antenna mentioned above is known as a helical antenna, they are possibly one of the easiest antenna types to build as a DIY project. The ones shown above are quite short so I would not expect the gain to be very high, although the quad-parallel configuration might yield better results.
For those interested in building a helical, lookup info on the Kraus formula. At some point when I have time I might put up an explanation of the math, but for now just have a look at http://wireless.gumph.org/content/3/11/cached_helical.html which does a fairly good job at explaining how to build one.
Useless factoid: Most satellites use circular polarization.
JAWUG