# [TowerTalk] 6m Moxon and F12 C3-SS Spacing?

Joe Subich, W4TV lists at subich.com
Thu Jul 16 16:01:48 PDT 2009

```The tribander should not be effected by the Moxon since
its elements are only about 1/4 wave on 10 meters.  The
real question is how close can you get the tribander
without effecting the 6 meter antenna.

The general advice for stacking VHF antennas is usually
half the published "stacking distance" for the higher
band antenna.  However, since there is no published
stacking distance specification for the Moxon, we have
to estimate it using a compromise formula (one source says
57/beamwidth ... the other says 52/beamwidth) and the
free space vertical beamwidth for a Moxon (142 degrees).
Using that compromise/estimation, we get a stacking
distance about 7.6 feet (55/142*984/50).

Given all that, I'd recommend putting the Moxon 5 feet
(at least 1/4 wave) above the tribander just to have a
bit extra space.  The Moxon is certainly not a big
antenna (approximately 7' wide x 3' boom if my
calculations are correct) so should not generate much
stress on a mast/rotor/roof tower at that height.

73,

... Joe, W4TV

> -----Original Message-----
> From: towertalk-bounces at contesting.com
> [mailto:towertalk-bounces at contesting.com] On Behalf Of Eric Rosenberg
> Sent: Wednesday, July 15, 2009 2:50 PM
> To: PVRC REFLECTOR
> Subject: [TowerTalk] 6m Moxon and F12 C3-SS Spacing?
>
>
> My tribander (a Force 12 C3-SS) sits on a roof tower approx.
> 6 ft above the peak of my roof.
>
> I'd like to add an Ariane Arrays (now-defunct) 2-el Moxon
> above my tribander and below the horizontal element of my
> 160m wire that runs almost directly over it.
>
> My question:  What's the stacking distance?  Ariane said 3
> feet if I off set it 90 degrees from tribander.  Others have
> said 15 feet regardless.
>
> When dealing with a roof tower, this is a HUGE difference!
>
> My primary concern is the potential degradation of the
> tribander's performance.
>
> 73 & Thanks,
> Eric W3DQ
> Washington, DC _______________________________________________
>
>
>
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```

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