They are combined. Nextel does this and calls it a "Quasi-Omni" site. There are some drawbacks to it, but it actually works quite well. Most panel antennas used are 90 or 65 degree antennas. The biggest drawback is the 6dB hit that you take on receive and some strange nulls between the sectors. The 3-diversity receive scheme they use seems to help in these areas.
As you stated, a voter would be the best solution to the water tank site. But. what would you do about transmit? Switching the transmit would eliminate the omnidirectional coverage that you need for mobile-to-mobile communications. This would start to get to be a very complex system. I was trying to keep it simple a affordable. Joe -------------- Original message ---------------------- From: "Eric Lemmon" <[EMAIL PROTECTED]> > Joe, > > I don't think those three panel antennas are combined at all. Most cellular > and PCS providers are using 120-degree panel antennas to cover three > 120-degree sectors, each with its own base station, effectively tripling > their capacity. The older omnidirectional antenna cell sites- usually a > cluster of fiberglass vertical pairs, one pointing up and one pointing down- > are being retrofitted with panel antennas. Panel antennas are much easier > to camouflage, and they can be physically tilted for better close-in > coverage. > > One solution to obtaining omnidirectional coverage around a water tank- > assuming your site owner will allow you to put up three antennas- is to use > a voter to select the best signal from three low-gain Yagi antennas, and > switch the transmitter output to that antenna. I suppose combining would > work, but I wonder if destructive cancellation will rear its ugly head. > > 73, Eric Lemmon WB6FLY > > > -----Original Message----- > From: Repeater-Builder@yahoogroups.com > [mailto:[EMAIL PROTECTED] On Behalf Of Joe > Sent: Saturday, January 27, 2007 3:17 PM > To: Repeater-Builder@yahoogroups.com > Subject: Re: [Repeater-Builder] Re: Antenna on the side of a water tower > > <snip> > > One of the carriers does something similar. They put panel antennas on > each of the 3 faces, then combine them into one omni-directional antenna > system. It does work. I know of several water tank installations that are > just like this. > > Joe > >
--- Begin Message ---
Joe,
I don't think those three panel antennas are combined at all. Most cellular
and PCS providers are using 120-degree panel antennas to cover three
120-degree sectors, each with its own base station, effectively tripling
their capacity. The older omnidirectional antenna cell sites- usually a
cluster of fiberglass vertical pairs, one pointing up and one pointing down-
are being retrofitted with panel antennas. Panel antennas are much easier
to camouflage, and they can be physically tilted for better close-in
coverage.
One solution to obtaining omnidirectional coverage around a water tank-
assuming your site owner will allow you to put up three antennas- is to use
a voter to select the best signal from three low-gain Yagi antennas, and
switch the transmitter output to that antenna. I suppose combining would
work, but I wonder if destructive cancellation will rear its ugly head.
73, Eric Lemmon WB6FLY
-----Original Message-----
From: Repeater-Builder@yahoogroups. com
[mailto:Repeater-Builder@yahoogroups. ] On Behalf Of Joecom
Sent: Saturday, January 27, 2007 3:17 PM
To: Repeater-Builder@yahoogroups. com
Subject: Re: [Repeater-Builder] Re: Antenna on the side of a water tower
<snip>
One of the carriers does something similar. They put panel antennas on
each of the 3 faces, then combine them into one omni-directional antenna
system. It does work. I know of several water tank installations that are
just like this.
Joe
--- End Message ---
