On Fri, 6 Nov 2009 08:05:17 -0800 (PST), Art Unwin
wrote:

On Nov 5, 10:11*pm, tom wrote:
Art Unwin wrote:
What is the best antenna for use with all circular, horizontal,
vertical and other polarizations without drastic fall of in gain, and
without changes in angular position and feed point via switches e.t.c
at the tower top?

Maybe the quadrifilar helix.

tom
K0TAR

That is made for a single circulation signal only.

It might be done with 4 quadrifilar antennas. Each antenna has a
hemispherical pattern and one sense (left or right hand). With 4
antennas and a suitable combiner, each antenna will cover one half of
the pattern, and one of the two available senses. The quadrifilar
antenna will work with linear polarization, but at reduced gain. The
usable bandwidth is probably insufficient to cover DC to light, but
multiple quadrifilar antennas can be attached to the surface of a
ball, resulting in a sperical pattern approximation and a construction
that looks like a puffer fish. It's also possible to conglomerate the
quadrifiler into a tapered helix, thus increasing the bandwidth at the
expense of gain. For VLF, shove a ferrite rod into the middle.

You can also do random polarizations by using leaky coax, tangled into
a Gordian Knot. Some part of the knot will undoubtably be parallel to
the random polarization, and thus provide some signal pickup. Gain
will be limited by the length of the lossy coax and size of the knot.
http://www.afltele.com/products/fiber_optic_cable/coax_cable/leaky_coax/
http://en.wikipedia.org/wiki/Gordian_knot

Marginally related drivel:
http://www.wifi-plus.com
http://www.connectronics.com/wifi_plus/
"The world's first MULTI-POLARIZED - MULTI-PATH Antenna with
GEO-Spatial capture".


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