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[TowerTalk] Optimum Stacking Distance

To: <>
Subject: [TowerTalk] Optimum Stacking Distance
From: (alsopb)
Date: Sat, 28 Jul 2001 13:39:39 +0000

I understand you did extensive analyses considering the terrain around
you.  To what extent did this impact the stack spacing and/or final
antenna heights?

73 de Brian/K3KO

Bill Tippett wrote:
> KQ2M:
> "What happens if the elements are several feet in from the ends?
> Do we still use the boomlength as expressed in wavelengths, or do we use the
> actual length between the elements?"
> Hi Bob et al!
>         Boomlength is distance between reflector and the last director.  
> WX0B's
> SQRT [boomlength] is only an approximation and you should model it exactly
> as others have suggested.  My 10M antennas are .791 wl long, WX0B's model
> suggests .889 wl spacing, but EZNEC said 1.007 for maximum gain.  If you
> really want to do things right, use YO7 which will let you optimize much
> more rapidly and flexibly than EZNEC.  K6STI is still in business and can
> be contacted at  I put my KLM's up with stock dimensions since
> I was in a hurry, but later retuned them for ~1 dB more gain, ~8 dB more F/B
> and better bandwidth over 28.0-28.8.
>         I believe better RX patterns are more important than small 
> improvements
> in gain, so I optimized with higher weighting to F/B.  I also discovered that
> better F/B can be obtained with wider separations.  You can see this in YO7
> as you optimize with different stack separations.  I verified the F/B using
> another RX antenna ~500' away from the stack.
>         Another point...YO7 would allow you to mount the elements at the
> ends of your boom and take full advantage of the boom length you have.  It's
> a waste to not use every available inch of boom you have since the wind
> loading, weight, etc are essentially the same.  If you have several stacks,
> the cost of YO7 would be well repaid IMHO.
>         I'm very happy with my stack holds alltime USA SOSB10 records
> for both CQ WW's, both CQ WPX's, ARRL DX SSB and ARRL 10 CW (missed ARRL DX CW
> by 0.21% last year and it appears I missed it for 2001 also...connector 
> failure
> during the middle of EU run!)
>                                                 73,  Bill  W4ZV
> P.S.  This is not a paid YO7 commercial...I just happen to be a big fan of it
> because it has worked so well for me!
> -----
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