FW: [FoxHunt] Turnstile antennas for 2M

[John Munsey, KB3GK]

I don't like the L'Per so don't own one.  XTAL frequency control is too 
restrictive.

I do have and use (sometimes) the BMG.  I have one for 2 meters and one for 
70 cm.   Generally, at a distance they are used vertically but on every 
hunt, where I use them, I always turn them flat and sweep the horizontal 
signal.  Works very well with no problems and no changes needed.  It is, 
generally, much sharper than in the vertical mode.

The same applies to my beams (various designs)  I use everyone of them in 
the Horizontal position on every hunt, especially as I close in or find 
myself in deep woods.  No problems at all and not "modifications needed" 
just do it and it works.


At 12:06 AM 1/17/2004 -0800, bob wrote:
>Good points...
>
>Except when you expect a runner to carry a pair of turnstiles separated by 
>a ways. I have run my TDOA BMG sniffer with small loops with some success. 
>The LPER is harder to "loopize", but it is possible. Note I didn't say it 
>was not possible, but just difficult. I dunno how to do the Adcock in H-pole.
>
>Bob, WB6JPI
>
>Kuon & Dale Hunt wrote:
>
>>>From: bob <wolfbob@csnsys.com>
>>>
>>>...The Yagi and most directional antennas are directional
>>>in both planes about the same...
>>>
>>
>>
>>   Actually not.  The half-power beamwidth is different for
>>   the E and H planes, especially for shorter beams as would
>>   be typical of ARDF.  This is clear if you consider a 1-element
>>   antenna - the dipole.  When vertical it is omnidirectional,
>>   but when horizontal it has directivity with nulls off the
>>   ends.  Extended to 2- or 3-element yagis there is still a
>>   significant improvement in directivity when used horizontally,
>>   and the front/side ratio is greatly reduced due to the
>>   null off the ends of the elements.  This difference is not
>>   as noticable for long yagis, but is still visible in the
>>   free-space patterns.
>>
>>
>>
>>
>>>It does rule out using a lot of direction finding
>>>techniques such as dopplers and LPers as they are most difficult to get
>>>going H-Pol.
>>>
>>
>>
>>    Actually not that hard, as long as you have omnidirectional
>>    horizontally polarized antennas to use instead of the
>>    usual whips.  This could be a turnstyle, halo, or small
>>    horizontal loop of some sort.  Two of the latter would make
>>    a small TDOA rig, or, with a phasing line, would allow a
>>    L'Per to be used.  If you really want to be creative you can
>>    extend either principle to 80m antennas!  The theory is all
>>    there in Jasik, Kraus et. al.  Just requires someone crazy
>>    enough to try it, and not worry how practical it really is.
>>
>>
>>---
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>>
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>>
>>
>>
>
>
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Sincerely,
John Munsey, KB3GK



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