[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. 


   ... 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
> 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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