[TowerTalk] 40 and 20 at 15 ft apart

ROBERT HARMON k6uj at pacbell.net
Mon Aug 29 07:45:51 PDT 2011


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 Aug 28, 2011, at 4:13 PM, Felipe J. Hernández wrote:

> 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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