I've modeled various homebrew, low-band colinears side-mounted off small
towers, and been surprised to see the same thing...nearly perfectly round
patterns, but with the center offset from the tower's physical location in the
direction of expected gain. I've never tried modeling anything like a water
tower leg, or other massive support...
73,
Paul, AE4KR
----- Original Message -----
From: Jim Brown
To: Repeater-Builder@yahoogroups.com
Sent: Wednesday, July 01, 2009 4:46 PM
Subject: Re: [Repeater-Builder] DB-224 patterns on side of tower.
Back when we had to submit an antenna pattern in order to get a
repeater license for the ham bands, I mounted four elements of a DB-224
directly on one leg of a Rhon 25 tower and mounted the two tower sections on an
antenna test pedestal and ran the pattern. With the antenna sections directly
in line and pointed away from the tower, we had 9 dB gain in the favored
direction, 6 dB gain at plus and minus 90 deg, and 3 dB gain off the back side
of the tower.
The plot was perfectly round with the 3 dB offset for the center point
of the plot.
73 - Jim W5ZIT
--- On Tue, 6/30/09, tahrens301 <tahr...@swtexas.net> wrote:
From: tahrens301 <tahr...@swtexas.net>
Subject: [Repeater-Builder] DB-224 patterns on side of tower.
To: Repeater-Builder@yahoogroups.com
Date: Tuesday, June 30, 2009, 2:35 PM
Hi Folks...
According to DBprod, it would give the appropriate pattern
for our desired area. However, one of the old salts here
(who has final say-so) says that you really have to put some
left and right angulation on the elements to get that pattern...
.
