[FoxHunt] Turnstile antennas for 2M

Thu, 15 Jan 2004 09:52:54 -0600

Marvin is right, if you have ever hunted in deep woods, vertical polarization
gets absorbed by the vertical tree trunks. A vertically polarized signal will
appear to be horizontal just a few hunderd feet away. The DFing antennas are
also have a better pattern when horizontal.

Tony
AA9CC

Quoting Marvin Johnston <[email protected]>:

>
> Horizontal polarization has been used for years on 2M ARDF hunts over in
> Europe. From the people I've talked to, there are several reasons that
> include less effect from the vertical attenuators out on the course
> (trees.) Apparently it is also a bit easier to differentiate between
> reflections and the real signal.
>
> I might add that the signals are AM over there, and not FM as is
> commonly used here in the US.
>
> As far as hiding, ARDF transmitters are identified by an Orange/White
> Orienteering flag that are usually visiable from at least 10 or 15
> meters away. Unlike some of the mobile hunts I've been on, the idea is
> not hider vs hunters, but rather to provide a fair venue for hunters to
> compete against themselves. The challange is navigation, not trickery
> :).
>
> If anyone is interested in the Region I ARDF rules, they can be seen at
> http://www.ardf-r1.org/, and look under "ARDF Rules".
>
>
> bob wrote:
> >
> > Why did they decide on horizontal antennas? Verticals are so much easier
> > to make, hide etc.
> >
> > I will be building one and probably use it on an up coming mobile hunt.
> > It will make for some very interesting reflections from the bottom of a
> > canyon.
> >
> > I notice that you crumpled the 90 degree phasing harness into a wad and
> > stuffed it into the pipe. The outer conductor of the phasing harness has
> > lots of RF on it and this isn't a good place to put it. Better to let it
> > dangle with the coax. You could also dangle a 1/2 wave loop for a balun
> > (although it doesn't have RF on the outside and could be crumpled up),
> > removing most of the RF on the feed line.
> >
> > Bob, WB6JPI
> >
> > Jay Hennigan wrote:
> >
> > >I've assembled a number of these recently.  Details here:
> > >
> > >http://www.west.net/~jay/turnstile.html
> > >
> > >Comments, criticism, flames, etc. welcome.
> > >
> > >
> > >
> >
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