In , Earl Johnston
wrote:

On Thu, 10 Jul 2003 07:16:18 -0700, Frank Gilliland
wrote:

Circular polarization of a signal is caused by "Faraday rotation" as a signal
passes through the upper atmosphere, and occurs mainly with frequencies from 100
to 1000 MHz. Unless you plan on tuning in on satellites in that frequency range,
an antenna designed for circular polarization isn't going to do much good. IOW,
the term was probably adopted into CB mythology to describe a helical antenna,
which is no more efficient than any fiberglass stick antenna, and less efficient
than an unloaded whip.

Nearly all CB radio antennas are vertical, and therefore vertically polarized.
You are wasting your resources trying to make an antenna that's capable of
receiving both vertical and horizontal polarization. For lots of antenna
information, here's a good place to start:

http://www.ac6v.com/antprojects.htm


Thank you for the advice, and there is a L-O-T of information at that
site.

The circular polarized beam antenna idea is not unique to Lou
Franklin. I have seen the same concept promoted by Jo Gunn Antennas

"V Series (DX Antennas) - The V Antennas have a single feed line which
transmits circular polarity. This is the most effective way to talk DX
and hold the conditions the longest. For CB'er who wants to get the
most out of his skip talking, the V's will give the best performance
possible."

http://www.jogunn.com/jgwhich.htm

I had the impression that the Jo Gunn antennas were quality products
with solid design.

I understand that for those of you in the United States, CB is
restricted to ground wave communication. However, others in this
forum are able to talk skip without running afoul of our national
regulations.

Leaving aside the question of whether or not one should talk skip on
CB, Are Lou Franklin and Jo Gunn Antennas just blowing smoke, or is
there anything in their claims that CP beams are best for skip
talking?



Smoke city. It takes a helical antenna to radiate circular polarization. Those
fiberglass CB antennas are called 'helical' only because of how they are made,
not because they radiate circular polarization (which they don't). Want to see a
true helical antenna?

http://www.cc.edu/physics/radtel01.html

That's 30 inches long for 2400 MHz -- now can you imagine the size of a helical
for 27 MHz?

The Jo Gunn antenna you cited is called a V-yagi, and is just another variation
of the basic yagi design. Assuming it is mounted horizontally, it's polarity is
horizontal, not circular.

Here's a couple more links on antennas that I should have posted first:

http://www.tmeg.com/tutorials/antennas/antennas.htm
http://www.cebik.com



"The more we understand, the better our choices will be." -- L. B. Cebik, W4RNL





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