You hit the nail on the head on the difference.... Mounting. And then
additionally F/B ratio.
When it comes to Horizontal 900 120 sectors, options are limited. A 4 ft -
15" wide antenna takes a lot of wind abuse.
We use the MTI's occasionally, for low to ground installs. Or where we can
mount the antenna to a structure that already has mass to create isolation,
like brick penthouses, or when we mount on seperate sides of a hill, and
have the dirt help F/B ratios, or when its just a single sector on a thinner
pole. But when we go up on a tower, I'd never take a chance with one of
the hose clamp mounts, its not worth the liability at 300 feet up. For
tower mount, where we do three sectors, I only use Tiltek. They have 20db
F/B, which is needed for close mounting, and solid mounting hardware for up
to 4.5" pole. For around $530 at Winncomm, its the way to go.
However, the mount is over engineered, for a simple low to ground mount.
Shims are required to attach to 2" pole. So for low to ground, low risk
installs, where its easy for inspection, and antennas don;t need to be right
on top of each other, its easier and cheaper to just use the
MTIs/Teletronics.
Depends on the need.
The thing to remember is that F/B ratios are generally MAX isolation, not
minimum. So when you are doing 120 sectors, the adjacent sectors overlap a
bit. With only 3 sectors in 900, its not possible to skip every other
channel like 5.8, so antenna isolation becomes a much bigger deal, and how
sharp the cut off on edges. What antenna to use, depends on your isolation
characteristics that you are mounting to.
This is a tiltek.... \ _ / with two metal fnages to help isolate and
have a tight cut off on edges.
Here is the MTI... _ Just the panel itself.
Which do you think will work better for isolating from the adjacent sector
antenna closely mounted on a tower?
Here is where I use MTI.... / \ or
\ I
Big fat hill
I 50 feet of verticle seperation minimum
or Penthouse
I
__
I /
Just my opinion.
Tom DeReggi
RapidDSL & Wireless, Inc
IntAirNet- Fixed Wireless Broadband
----- Original Message -----
From: "Mike Bushard, Jr" <[EMAIL PROTECTED]>
To: "'WISPA General List'" <wireless@wispa.org>
Sent: Wednesday, November 22, 2006 11:41 PM
Subject: RE: [WISPA] 900 antenna question
Why don't you just get these?
MT-243015/NH - 902-928 MHz 11dBi 180° Horizontal Pol.
It's made by MTI, the same brand as the Teltronics.
We run MTI 120's for all of our Horizontal towers (17 of these antennas
deployed total right now). The mount scared me a little though, it is a Cast
"V" (Same style as the Orthogon Radios) and then you secure it with hose
clamps. It seems to work well thought. I think the down tilt gauge is kinda
cheesy, so we bought a incli-meter from the local tower crew.
Mike Bushard, Jr
Wisper Wireless Solutions, LLC
320-256-WISP (9477)
320-256-9478 Fax
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Brian Rohrbacher
Sent: Wednesday, November 22, 2006 10:24 PM
To: WISPA General List
Subject: Re: [WISPA] 900 antenna question
I don't know but until now the best 180* antenna I can find is the 8dbi
from superpass (which I installed today and were crap). This one looks
nice.
Brian
Travis Johnson wrote:
Hi,
Looks to me like it's about 5db off at 180 degrees. What's the price
on this antenna?
Travis
Microserv
Brian Rohrbacher wrote:
http://www.teletronics.com/15-404.pdf
What would the gain at 180* be on this antenna. I want to make sure
I am reading it right.
Brian
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