"Art Unwin" wrote in message
...
On Sep 8, 6:49 pm, Richard Fry wrote:
On Sep 7, 6:44 pm, "christofire" wrote:

... and if that isn't enough, how about the Racal Antennas
athttp://www.racalantennas.com/products/ground/omnidirectional/hf/difan...

I just now looked at this link, and see that it states that this
radiator configuration is horizontally polarized.

That polarization appears to be "implausible" for this configuration.

Does any scientific documentation exist, or do any measured, real-
world performance results prove that this configuration truly is
horizontally polarized?

RF

You are so dumb! Look at the center pole as being a vector in
opposition to the gravity vector. Then add the two tilted vectors
which represents the vectors of the Coriolis force.
(Yes, you add both of the vectors for Coriollis because it is a
rotational force) You are then left with a horizontal vector that
balances the above vectors. Thus you have horizontal polarization.
Why? Because the vectors outside the boundary are a combination of
two vectors which is gravity and the Coriolis. Now somebody mentioned
the question of polarization purity ! When you include the Coriolis
effect you get exactly that, a pure horizontal polarization which is
very useful in determining whether forces in shear conditions exist at
airports as views of reflection of transmissions are confusing if
you transfer a mixture in the first place. This way they have purity
in radiation so that reflections are more clearer for their
determinations as to what weather conditions exist and hopefully not
"wind shear" where a plane instantly loses altitude.
You are fortunate that you caught me before I left.


None of that sounds very plausible.

What little experience I have of Racal Antennas would suggest they'll be
keeping the details proprietary, but there are some clues in the words of
their advertisement. A 'delta travelling wave antenna' is like half a
rhombic and deltas (i.e. 'V's) can be seen amongst the rigging - horizontal
ones and upward-tilted ones (as well as vertical ones, but they're probably
not driven differentially). A delta supports waves that have the electric
field developed between the two wires so a delta in the horizontal plane
would yield horizontal polarisation.

However, the drawing doesn't make it obvious which pairs of wires are driven
as the deltas, particularly when there appear be eight legs in the outer
ring and three in the inner ring. The words say there are three 'pairs of
delta travelling wave antennas' which probably means three deltas, that is,
three pairs of wires driven differentially - clear English was never their
strong point.

Googling 'difan' didn't yield anything useful so this may be Racal's own
design.

Chris