Personally, I think "it depends."
1. For instance, my setup (available land, a field) lends itself to putting
"main towers" (e.g. one for each band, 40, 20, 15 and 10) broadside to
Europe, so the antennas are all 90 degrees from each other when they're
pointed toward Europe. We do this with the W3AO Field Day with 10-12 towers
and it works very well, reduces inter-band interference, etc. It should
work well in a permanent setup too. It probably doesn't hurt either that
the house will be on this same line, so that the antenna are not pointed at
the house (hamshack) in their primary direction. This all should help keep
RF out of the shack and going to the DX stations where it belongs.
2. Greater distance is generally better, but there's the tradeoff, at
least, of longer feedlines. My feeling is the towers should be 100-150'
apart (minimum), assuming they're tall towers, like yours -- since 130' or a
little more allows for 80M half-wave antennas to be hung from the towers.
That's a good minimum separation, I think, since closer is definitely
getting pretty close and farther may not buy you too much more in
interference reduction, traded off against longer feedlines.
3. W3LPL's basic setup is a circle of 6 (I think I have the number right,
if not it must be 5) towers that are 140' apart (around the curve of the
circle that is). I think this was driven by county setback requirements on
his 10 acre property with 100 percent setback requirements -- he installed
all the towers including anchor points on just four of the 10 acres! The
separation, by design I think, allowed him to hang 80M 2-element quad wires
from those towers in 4 directions (using common reflector elements for
directional pairs). So, it worked out well, has been effective -- a
superstation on relatively limited real estate.
Others, obviously, have done a lot with even closer spacing. K3WW I think
has two towers pretty close together -- and I'm sure many others do too --
and it has been very effective.
But, if you're building a super station, even 130, 140, 150' spacing should
be sufficient to build a really big and effective station. Obviously, with
a lot more real estate like VE6JY or W0AIH or others your options open up a
lot more.
For my site, I'm going with the straight line approach for the main towers,
40 through 10 -- they're looking "off the property" and toward Europe so
they won't be looking at any other antennas in that direction, clear "field
of fire." In fact, it's 3/4 mile of parkland in that direction to the
Patuxent River, then a golf course on the other side, then a housing
development -- must be 1 mile and a half to the nearest house in the
direction of Europe. Can't hurt.
But, obviously a circle of towers (W3LPL), or diamond (The most recent W7RM
I think, more or less), or any other configuration can work well too.
73 - Rich, KE3Q
----- Original Message -----
From: "Keith Dutson" <kjdutson@earthlink.net>
To: <TowerTalk@contesting.com>
Sent: Tuesday, February 22, 2005 2:50 PM
Subject: [TowerTalk] Tower Spacing
> Is there a minimum spacing recommended in a multi-tower antenna farm? I
> currently have a 150 footer up with a stack of four Yagis. The next one
> will likely be 190 feet for an 80 meter Yagi at top and WARC Yagis below.
>
> Keith NM5G
>
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
> Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
> any questions and ask for Sherman, W2FLA.
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|