[Premium-Rx] Antenna information, NVIS , eliptical, etc..

[David McGinnis]

The NVIS antennas are well documented on the NVIS group on the Yahoo
refelctor.   Read the archicves there for information, join for
discussion.  Most typically, the miltary AS-2259 (crossed dipoles, at
"anti-resonate" lenghts),  full wave loops, Jamaca dipoles (phased),
Shirley dipoles (phased) and low dipoles.  

Read the book NEAR VERTICAL INCIDENCE SKYWAVE COMMUNICATIONS by LTC
David Fiedler and MAJ Edward J Farmer.    Its $14 from world radio
books.  Read the book before discussion, it will save lots of questions.
 Its an easy read.

There is quite a bit commercially done with HF antennas we never see in
the hobbiest world.  Look for eliptical horizontal antennas (spira cone)
of the Granger line from Andrew Corporation for instance.  This antenna
is broadband across the entire HF spectrum, omnidirectional (with out
major nulls or lobes), exhibits roughly 6dbi gain, same as a dipole, and
can be used with up to 4 different radios with either high angle or NVIS
propagation.  Yeah, okay it probably cost 40,000 too.   The Andrew
government antenna products web page is:
http://www.andrew.com/products/antennas/government/default.aspx#
Scroll down to HF Antennas and pick technical litature from the drop
down.  Lots of .pdf on their products.  Look up the details on the
patent numbers to see how it works.  Some of the antennas at the HARP
project are Andrew eliptical spira-cones.  Andrew isnt the only company
that is playing with eliptical polarization with HF antennas.  There are
a few variations on the theme from different companies.  

Dave