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[CQ-Contest] Stacking 2 x 4ele 10M yagis

Subject: [CQ-Contest] Stacking 2 x 4ele 10M yagis
From: btippett@alum.mit.edu (Bill Tippett)
Date: Wed May 29 21:32:17 2002
G0CKP/AB6ZA wrote:
>I have 2 x 4ele 10M Force-12 yagis

        You should definitely stack them vertically.  This will
give you versatility in takeoff angle selection if you can feed
either separately or both in phase (maybe even both out of phase).  
If you stack them horizontally at 70', you are stuck with one set 
of takeoff angles and you will also narrow the horizontal beamwidth
which is a disadvantage in contesting.  Plus you could point them
in different directions if you used a sidemount system which is
invaluable in contesting.  I'm not sure what vertical polarization 
might do but all your neighbors would probably think you were a 
CB'er!  ;-)

        I assume you have the EF-410 which is on a 12' boom.  The 
optimum vertical stacking distance for this boom length is in the 
range of 20'.  12' is definitely too close for them to work 
properly.  A quick look using YO7 shows you would get about +1 dB
gain at 20' instead of 12' spacing, with about the same F/B.  I
would go for one at 50' and the other at 70', or possibly even
greater spacing like 35-40' and 70' to maximize takeoff angle
coverage.  If it were me, I would also invest $100 in YO7 and
optimize the antennas for performance as a stack...VERY simple 
to use and well worth the performance improvement you would get.

                                      73,  Bill  W4ZV

P.S.  My 3-stack at  http://users.vnet.net/btippett/images/W4ZV.htm

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