A couple of things need to be taken into consideration to arrive at the best
First, is your repeater centrally located to your intended audience? If the
answer is yes, some are likely going to be unhappy with the shadowing of a
side mount. Depending on the length of the sidebar you could easily have a
deep null, more than 5 dB, on the tower side.
Second, what are the chances of a lightning strike in your area? If they
are high, you will likely be climbing that tower often to replace the
antenna if it is mounted on top. My club has replaced the repeater antenna
an average of once per year due to lightning strikes. That antenna is
installed on the roof of a tall building. OTOH, I had a 144/440 dual bander
mounted at the top of the mast (rotated) on my tower that lasted 4 years
before being blasted into several pieces by a strike, so you might get
Pick your poison.
[mailto:firstname.lastname@example.org] On Behalf Of K5XS@aol.com
Sent: Wednesday, January 05, 2005 1:37 PM
Subject: [TowerTalk] Omni Directional Antenna on Tower
I am putting up a small (50') dedicated VHF/UHF tower to "declutter" my main
I operate a UHF repeater from my QTH, and am considering putting an
omnidirectional (colinear) antenna on the tower for the repeater to take
advantage of the added height over the present antenna location.
Two configurations occur to me:
1) Putting the repeater's omni antenna on the side of the tower with a
cross-arm. I would need to install a cross-arm and would have a little
shadowing from the tower.
2) Putting the omni antenna on the very top of the mast. Naturally, the
antenna would rotate whenever I rotated the 6-meter and 2-meter horizontal
yagis, and I am concerned about flex in the coax and N connector over time
and about increased susceptibility to lightning (not a major risk here, but
Does anyon have any thoughts? Option 2 is appealing, but it sure seems dumb
to rotate an omnidirectional antenna...
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
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