The problem is there are 2 (major) different goals in stacking... max gain,
which you can really only estimate in free space or above a perfect flat
earth, or for very high vhf arrays... or covering all the takeoff angles
over the earth that you have to work with. If you are quoting a distance
between antennas that can only be something theoretical for some kind of max
gain figure. Otherwise you need to study the real terrain and the resulting
takeoff angles to fill in the gaps so that you can cover all the expected
angles. Two antennas might be able to cover all the angles, but in my
situation I went with 4 because it really filled in the high angle stuff
where the top antennas had major nulls at otherwise useful angles. For
studying the takeoff angles you must take each antenna separately, don't
count on additional gain from adding two antennas together, assume each one
is separate and fill in the gaps in the vertical pattern of one with another
one farther down the tower.
David Robbins K1TTT
e-mail: mailto:k1ttt@arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://k1ttt.net:7373
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Randy
Lake
Sent: Wednesday, August 10, 2016 00:08
To: john@kk9a.com
Cc: towertalk@contesting.com; Richard (Rick) Karlquist
Subject: Re: [TowerTalk] Stacking question
My feeling is that the antenna manufacturer is the one to get the stacking
distance data. From there one can use HFTA to get an approximation of stack
hight.
Randy N1KWF
On Tue, Aug 9, 2016 at 2:13 PM, john@kk9a.com <john@kk9a.com> wrote:
> I am saying that HFTA is not a good tool for modeling stacking distances.
> I also disagree with your max distance stacking numbers.
>
> Sent from my Smartphone.
>
> On Tue, Aug 9, 2016 at 11:21 AM, Richard (Rick) Karlquist <
> richard@karlquist.com> wrote:
>
> >
> >
> > On 8/9/2016 7:03 AM, john@kk9a.com wrote:
> >
> >> I have no HFTA experience however after looking at the stacking
> distances
> >> from people that have used it I would not recommend it. It puts the
> beams
> >> way too close together in my opinion.
> >>
> >> John KK9A
> >>
> >> high for you! I've stuck with the M2 recommendations - and have in
> >> modeling confirmed they work well. That is 60' on 20 and 45' on 15.
> >> The
> >>
> >> Gary
> >> K9RX
> >>
> >>
> > According to my modelling, 60' on 20 and 45' on 15 are near the
> > MAXIMUM stacking distances, being nearly a wavelength. Did I
> > misunderstand what you were saying?
> >
> > Rick N6RK
> >
> _______________________________________________
>
>
>
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>
--
Randy Lake N1KWF
73 Gunn Rd.
Keene,NH
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