[TowerTalk] Optimum yagi stacking distance

[W0MU Mike Fatchett]

I am planning on stacking another 4 ele SteppIR on my tower.  I 
currently have a 4 ele SteppIR at 70ft.  I do not live on flat ground. 
Running HFTA it became clear that the top antenna was too high on 10 and 
15 and I had some fairly significant holes.  Some of this is caused by 
the hills around my QTH.  I wish I lived on a hilltop but I don't.

My model showed that stacking the 2nd antenna around the 30ft height 
would help optimize the pattern.  I need to do a bunch more work with 
HFTA and decide if that is indeed where I want the antenna to be.

You also need to look at what types of contests or operating you do. 
For DX work 70ft on 20m is ok but not great.

David Robbins K1TTT wrote:
> In most cases when vertically stacking hf antennas you are not looking for
> 'increased performance' as in adding the two patterns to maximize the lowest
> angle lobe or a horizontal pattern.  In most cases you are looking to fill
> in gaps in the vertical takeoff pattern... those pesky nulls that may fall
> in useful takeoff angles into Europe or your preferred target area.  
> 
> When stacking 2 yagis the best compromise is usually one on top, and one
> about halfway down the tower.  Its even harder with tribanders, or maybe
> simpler, since each band is a bit different there may not be a best spot for
> all 3 bands.  There may be other slightly better combinations if you land is
> not relatively flat, big dropoffs may push the lower antenna down further to
> fill in the higher angle gaps.  Hills in the foreground may push the lower
> one up higher on some bands depending on how close and tall they are.
> 
> 
> David Robbins K1TTT
> e-mail: mailto:k1ttt at arrl.net
> web: http://www.k1ttt.net
> AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
>  
> 
>> -----Original Message-----
>> From: towertalk-bounces at contesting.com [mailto:towertalk-
>> bounces at contesting.com] On Behalf Of Gary Slagel
>> Sent: Saturday, January 19, 2008 16:15
>> To: TowerTalk
>> Subject: [TowerTalk] Optimum yagi stacking distance
>>
>> More questions from a yagi stacking rookie!
>>
>> I've been using the HFTA software to try and get an
>> idea of the optimum distance to stack a couple yagis
>> for best performance.  I'm stacking 10/15/20
>> tribanders for increased performance.  I was really
>> surprised that on most bands the optimum performance
>> seems to be with them separated by only about 10'...
>> for instance 65' and 56'!  I expected it to be more
>> like 20' to 30'!
>>
>> I wonder how this jibes with folks with real
>> experience?
>>
>> Thanks,
>> Gary
>>
>>
>> Gary Slagel/N0SXX
>> Lakewood, CO
>> http://marina.fortunecity.com/sanpedro/351
>>
>>
>>
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