[FoxHunt] Turnstile antennas for 2M

[bob]

Never noticed...35 years of transmitter hunting and I never noticed. I 
guess we don't have the dense forests in California to cause that much 
attenuation. I will look into it however, and use it on a hide if indeed 
the V-pol absorption is great.
All reflections from natural objects tend to make the signal more 
circularly polarized. I use this technique for mobile hunting with 
crosss polarized 5 el beams on the 4 runner and note the polarization 
ratio of bearings to evaluate if they are bounces.

Bob, WB6JPI

alevand@foxvalley.net wrote:

>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 <marvin@rain.org>:
>
>  
>
>>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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>>>
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>>
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