[VHFcontesting] Antenna stacking distance

[Robert Cumming]

I have all 6 of my 144 MHz+ antennas
mounted on one tower using a small 4'x8' "H" frame.  What makes this
interesting is on the "H" frame are mounted 6 antennas as follow:

Bottom right corner - M2 2M5WL (17 elements, 33' boom), Bottom Left corner
Directive Systems 47 element Looper for 903 MHz.  At the top corners are a
Tonna F9FT 55 element beam for 1296 and a Directive Systems 76 element
Looper for 2304.  in the middle of each side of the "H" frame are mounted
a  222-7WL (23 elements, 33' boom)
and a 432-13WL (38 elements, 33' boom).  I'm still trying to figure if (and
how) I want to mount the 10GHz dish on this setup on a permanent basis.

My 222 antenna is located on one side of the "H" frame about 5' up from the
bottom corner (above the 903 looper).  This puts it about 6.4 ' diagonally
from  the 2M beam.

My reasoning for putting the 432 antenna above the 2M antenna and not the
222 antenna was just the reason you stated - to prevent interaction.  Using
the "H" frame was an idea given to me by Steve of Downeast Microwave fame
when I was trying to figure how to mount loopers for 903 and 2304 on one
mast with the existing antennas for 144, 222, 432 and 1296.  The 4'x8' "H"
frame was fabricated by directive systems using 1.5" Schedule 40 aluminum
Tubing.

There is no problem with swr on any band - I'm not too sure if there is any
degradation of the patterns of the antennas by this arrangement but they
perform well.

As to masting I have used 1 1/2" galvanized steel water pipe for 10" 
(about 8' above the thrust bearing on a model H4 Hazer on a Rohn 25 
tower).  I have never had a mast failure here in Central Florida 
(even through 3 Hurricanes last year)  I lower the hazer all the way 
and wrap the 1/4' guy wires around the tower and the mast.

Recently I acquired a "free" US tower TMM 541 tower (5 crank up 
sections for 41')for the price of taking it down and hauling it away 
(so far its cost me about 2.5K$ in concrete, mast, thrust bearing and 
new rotator).

As to the mast I went with a 20' ChromeMoly mast from Array 
solutions.  About 18' will extend above the top Thrust bearing and 
support Stacked M2 2M-5WLs Stacked at the 14' distance recommended by 
M2.  Above the bottom 2M-5WL I am placing a KT-34 with M2 Mods and a 
6M7JHV above that topped by the 2nd 2M-5WL.  All that will be turned 
by a Prosistel 2061 rotor also from Array 
Solutions.  Optimal?  Probably not but it gets HF thru 2M on one 
tower and frees up space on the existing VHF+ tower (one of the 
2M-5WLs came off it) for another 432-13WL stacked below the existing 
one.  (also planning to mount another vert tube on the "H" frame for 
a 3456 looper).

I can send pictures to you if you want.

VRY 73
Bob Cumming
W2BZY
QRV 160M-13CM + 3CM
from EL98hr

At 06:12 AM 11/7/2006, Ed Swiderski, KU4BP wrote:

>Hello all,
>
>I'm in the planning stages on a home station and was wondering about the
>stackiing distance for antennas for multiple bands. My plan is for 3, maybe
>4 on one mast or two medium size towers with 2 each. I have 16el on 2m, 18el
>on 432 and plans are for 5el on 6m and 220 is in the works. I've seen a
>couple solutions and was wondering what has worked best for you. One was to
>mount the lower freq beam a distance of half the boom length of the higher
>freq beam that's above it. Another was use the stacking distance
>calculations provided by the manufacturer. Which says to mount the higher
>freq beam at half the stacking distance of the lower beam.
>
>Can anyone shed some light or provide some links, formaulas etc on the
>proper way to stack multiple beams of different freqs on a single mast?
>
>Thank you,
>Ed Swiderski KU4BP
>EM96
>
>
>
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