On Sat, 5 Sep 2009 20:30:30 -0500, (Richard
Harrison) wrote:

Art wrote:
"Chris, what I believe he is referring to is that computer programs
support a tipped vertical over one at right angles to earth."

Quick! Tell your local broadcaster.

We don`t need theory to show that antennas for transmitters and
receivers work best together when they are exactly parallel in space
unless something in the transmission path is redirecting the
polarization of the signal. In aligning microwave antennas humdreds of
times, I`ll swear this is true every time, regarfless of Corriolis, no
matter which side of the equator I was on. Try it. You`ll be convinced
too.

Best regards, Richard Harrison, KB5WZI

Ummmm.... Faraday Rotation?
http://en.wikipedia.org/wiki/Faraday_effect
It's not too horrible at microwave frequencies, but becomes noticeable
as the frequency decreases. I've done some crude polarization studies
at VHF and UHF frequencies with a rotating dipole, and found some
rotation on line of sight paths. However, we were looking for a
polarization distribution and didn't really spend any time getting
accurate numbers for a line of sight path.

Also many broadcasters use elliptical polarization (a mix of
horizontal and vertical). However, that's not to eliminate any
Faraday Rotation effects. It's to deal with the effects of
reflections and refraction, which create nearly random polarization at
the receiving end. Also, because stationary broadcast antennas are
horizontally polarized, while vehicle mounted broadcast antennas are
usually vertical.

I was once asked why the British drive on the left side of the road.
My instant answer was Coriolis Effect. I claimed that due to the
earth's rotation, it's easier to make left turns on the left side of
the Atlantic Ocean and easier to make right turns on the right side of
the Atlantic. It took an excessively long time for even the sharpest
student to catch the joke/hoax. Sigh.

Drivel: At 2.4GHz, most wi-fi wireless routers use vertically
polarized rubber ducky antennas. Yet, most laptops have their
antennas in the top of the LCD frame which are horizontally polarized.
Same with PCB antennas found on most PCMCIA cards.

Anyway, nobody cares much about antenna polarization:
http://picasaweb.google.com/lh/photo/HC8B4F-AnCQF6I_u0k3MYg
http://802.11junk.com/jeffl/pics/Old%20Repeaters/slides/LoopMtn03.html


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558