FW: [FoxHunt] Turnstile antennas for 2M

[bob]

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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