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Re: [TowerTalk] 40 and 20 at 15 ft apart

Subject: Re: [TowerTalk] 40 and 20 at 15 ft apart
From: "Felipe J. Hernández" <>
Date: Mon, 29 Aug 2011 21:37:20 -0400
List-post: <">>

So no 90 deg off for that combination? May I ask how far where they apart?

I guess is the right approach to then  model the antennas exactly..

I liked this explanation from Bob...

I have a Cushcraft D40 4 feet above a Force12  C3S tribander.
The D40 is aligned parallel with the boom of the C3S.
I have zero interaction between the two antennas.
I called Force12 and asked what they recommend for spacing before installing 
the antennas and
they said they recommend 4 feet wth the dipole parallel with the boom of the 
C3S.  Said this will give
negligible interaction (as I have found).
I would recommend calling or emailing them to discuss your planned installation 
and question.

As I understand the stacking situation, the current drop of multiband yagis, 
like the Force12 series,
have all the elements electrically insulated from the boom which provides very 
nice stacking possibilities
with minimal interaction.  The older design tribanders like the KLM KT34's had 
the parasitic elements
electrically attached to the boom and it is almost impossible to achieve a low 
interaction regardless
of height/orientation.


On 8/29/2011 9:03 PM, wrote:
> I have modeled 20m and shortened 40m beam interaction and with my antennas
> and the interaction was very minimal when pointing the same direction and
> very noticeable when pointing 90 degrees apart.  The antennas in your
> example may react differently, but I would recommend trying the same
> direction first.
> John KK9A / P40A
> To:
> Subject: [TowerTalk] 40 and 20 at 15 ft apart
> From: "Felipe J. Hernández"<>
> Date: Sun, 28 Aug 2011 19:13:31 -0400
> List-post:<">>
> Guys,
> Theres a great  benefit from turning the antennas 90 deg off.
> but Ive heard that, when you have a 40 and a 20 on the same tower, the
> interaction
> is never dissipated by the 90 deg offset.
> Is that true?
> Thinking of setting up a xm240 with a 3 or 4 el force 20 mtr monobander
> abt 15 ft apart..
> Thanks
> Felipe
> NP4Z
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