[Antennas] Force 12 Sigma SV5

[John Tait]

Hi all..
Subject: Re: [Antennas] Force 12 Sigma SV5


> I suspect this antenna is for real.  There is no rocket science to the
> design, just good logic.  If you take half of the length of a dipole
element
> out of the middle, you'll find that it radiates more than 80% of the
signal.
> What F12 has done is simply replace the 25% on one end with a T-Bar
> capacitive hat and an inductor in the middle.

  This antenna IS for real. The idea is around for years, and I'm glad to
see it coming to the fore. L B Cebik has quite a bit on the subject at his
website .. http://www.cebik.com/ He has a nice forty metre triangular arrray
for 40 m using this approach on the site. I've been using vertical wire
dipoles using this principle for quite some time. Shaped like a letter H
turned on it's side, the top and bottom horizontal wires act as capacity
hats, and the vertical portion is either centre fed, or fed at the at the
bottom junction with the horizontal wire. A good choke balun is a must in
this configuration.
          Compulsory reading on this subject should include  "Another way to
look at Vertical Antennas" by Dr Rudy Severns N6LF in QEX Mar/April 1999
edition. Also, Les Moxon G6XN's
book "HF Antennas for all locations" has interesting information on the
subject.

>
> This design is easily replicated.  The coil in the middle is for matching
> only, so it really does no radiating.  I've used a similar design with 10'
> elements and a 4' T-bar at each end.  I eliminated the loading coil in the
> middle and fed it with ladder line.  This 20' vertical performed
respectably
> on 40M-10M, was nearly invisible to neighbors (thanks to some tree
coverage),
> and also often outperformed my 35' high dipole in long-haul situations.
>
> The only caution is to bring the feedline away from the antenna at right
> angles.  This is an easy antenna to build, try it!

     Right on Paul... It is an EASY antenna to homebrew, can be 2
dimensional, low band versions are a lot easier to set up than the usual
ground plane on a "copper lawn", they're a lot more efficient than their
trapped/loaded brothers...and nice and CHEAP if you roll you're own...Not
cheap if you buy them, but "hat's off " to  Force 12 for "knowing a good
thing" when they see it..

            Vy 73
                      John EI7BA  http://www.iol.ie/~bravo/




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