[TowerTalk] Two 15m yagi stacking

[David Robbins K1TTT]

1. the separation distance is not as important as the vertical takeoff
angles needed from your location.  Hfta and other programs can help answer
that.  But with only 30m of tower to work with I would bet that one at the
top and the other 1/2 way up will probably be as good as you can do.
Remember, stacking like this is not all about big gain for contests, its
about covering all the angles so that you don't have a dead spot.

2. yes, that is good if you can't rotate the bottom one.  aim it where you
can get the most qso's and then combine them.  Note that you can also use
this to point them two different directions for when the band may be open to
two areas.  

3. I like 4 elements from the east coast of the states.  No, the gain is not
as high as 5 or 6 elements, but again in contests the idea is to cover the
whole area where lots of qso's are generated.  With 5 or 6 elements from
here you can not cover all of Europe without rotating them.  4 elements has
a wide enough pattern to cover most of the continent without losing much on
the north or south side.  So look at the pattern width compared to the range
of angles you need to cover, not just the max gain.  


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 BA7NQ Terry
> Sent: Saturday, February 24, 2007 01:16
> To: TowerTalk at contesting.com
> Subject: [TowerTalk] Two 15m yagi stacking
> 
> I am preparing make my first yagi stacking for contest station and
> researching some document from internet. The tower will have 30 meters
> high,
> and I have two 5 element yagi.
> 
> My question is:
> 
> 1) The separation distance between two yagi? Some documents said is 3/4
> wavelength, or 5/8 wavlength, or 0.62 wavelenght. How to consider this
> space
> vs stacking performance?
> 
> 2) My idea is, the bottom yagi fix to EU, and the top yagi is rotatable,
> when the top yagi beaming to EU, then switch the two yagi to "BOTH", is
> this
> right?
> 
> 3) About the YAGI, I found many station use 4 element or 5 element yagi
> for
> stacking,  is high-elements good for stacking or just 4 or 5 elements
> better?
> 
> Thanks for reading my message.
> 
> 73! de BA7NQ Terry
>