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Re: [TowerTalk] reflector for 75 meter inverted vee

To: towertalk@contesting.com
Subject: Re: [TowerTalk] reflector for 75 meter inverted vee
From: Bill Tippett <btippett@alum.mit.edu>
Date: Thu, 05 Oct 2006 17:15:16 -0400
List-post: <mailto:towertalk@contesting.com>

K4SAV:

 >Antennas arrays that provide large amounts of gain directed straight up
with very narrow lobes aren't very useful for ham purposes either.

         It depends on propagation.  At sunrise, sunset and during
high auroral activity, DX wave angles are often very high.  I
put up an inverted-V for 160 (apex 95') to complement my 3-el
vertical array.  95' is near the optimum height to maximize
radiation straight up.  You can see a TOA comparison of the
inv-V (blue) versus the 3-el vertical array (black) below:

http://users.vnet.net/btippett/new_page_10.htm

         The TOA break even point is about 40 degrees which can
be seen where the lines intersect.  ~95% of the time the vertical
is +10 dB over the inv-V, but ~5% of the time it's the other
way around.  One of those times was August 2 when I worked
KH8SI for #321 on Topband.  The vertical array simply did not
work (neither do Beverages for RX when angles are high) but
after sunrise his signal peaked very nicely on the inverted-V.
I'm very glad to have it for such times!

                                         73,  Bill  W4ZV




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