Towertalk
[Top] [All Lists]

Re: [TowerTalk] Antenna Side-mounted to Tower

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Antenna Side-mounted to Tower
From: "Dan Zimmerman N3OX" <n3ox@n3ox.net>
Date: Thu, 31 Aug 2006 01:55:45 -0400
List-post: <mailto:towertalk@contesting.com>
J-poles are somewhat sensitive to their surroundings and can be
sensitive to the feedline details... but if you're just looking for 2m
FM, as long as you can tweak it a bit on-tower you shouldn't have a
problem.  You don't exactly have a high-performance application in
mind if you're doing verticals on 2m, I expect.

That said, if you're doing a side mounted collinear you could consider
something like a 1/2 over 1/2 over 1/2 wave fed in the center with a
balun and coax... or even better (as you can get more gain) a phased
array of dipoles like they do for broadcast and repeater work, where
each element in the collinear is a separate dipole.  You can also put
them all around the tower and make your pattern more circular.

The question about how far away the antenna should be doesn't have a
single answer.  I think whoever told you you can't stick a J-pole four
feet away from the tower was being a bit paranoid, though.  I think
it's worth toting an antenna analyzer + balun up the tower so you can
tweak the coax tap points to give a good match at the antenna... but
don't sweat this one very much.

Dan
_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk

<Prev in Thread] Current Thread [Next in Thread>