Mark,
What ap antennas are you using there?
marlon
----- Original Message -----
From: "wispa" <[EMAIL PROTECTED]>
To: "WISPA General List" <wireless@wispa.org>
Sent: Saturday, February 03, 2007 2:58 PM
Subject: Re: [WISPA] Typical OFDM CPE antennas
On Sat, 3 Feb 2007 15:38:04 -0500, Tom DeReggi wrote
I wanted to get some feedback from the List.
Typically, what Dbi gain antennas are you desiring for OFDM short
Near-LOS or Mid-range CPE links? Is 18 dbi enough?
I'm well aware that 18dbi will not be good for many applications
(long range or noisy), but what percentage of CPE installtions would
it be good for? Could 75% of the CPE installs be acheived with 18dbi?
I personally, would pick a 21-23db antenna as a preferred choice,
but PacWireless Rootennas are 19dbi, and often used with 13-15 dbm
CM9 cards. The beamwidth of 18dbi (< 20-30 degrees) is pretty good
for interference resilience and OFDM maximized, and if more gain was
needed it could be accommodated with higher power radios such
Teletronic's >18dbm Atheros cards or Ubiquiti's SR5 18-26db cards.
Ok, where do I start... I can't tell that antenna design matters a bit
whether you're using OFDM or QAM or... ??? Seems the radio waves
propagate
the same.
I'm using 18 db grids out to well past 20 miles, with no amps and no high
powered radios (using CM-9's). I have ONE client with a 24 db grid at 17
miles or so, and he's got like a -60's RSSI. Doesn't even need it, but it
was mounted to his house when I hooked him up. So I saved myself 40 bucks
and used his.
I have one client btween 29 and 30 miles using a 16 db Vagi, from
Pacwireless. Again, no high powered cards, and he's got around 12 to 15
db
SNR ( -80 to -83). I was going to use a 19 db grid, but my antenna was
defective, and that was the only other thing in the van.
Star-OS access point, Compex WP54AG client board, running Ikarus.
I think our maximum throughput in 11b mode (won't work in G, sorry) was
350KB
or so. The customer is a 2M client, and we can get 2M in a speed test any
hour of the day or night.
My expeirience with G mode (not ofdm specifically) is that much higher
RSSI
is required to work at all.
I've seen OFDM clients work fine for 900 mhz at -85, so long as you
weren't
hoping to get past 1M throughput in a 5mhz wide channel.
My first 40 clients were ALL 18 db grids, be they 1 mile or 23 miles.
Tom DeReggi
RapidDSL & Wireless, Inc
IntAirNet- Fixed Wireless Broadband
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Mark Koskenmaki <> Neofast, Inc
Broadband for the Walla Walla Valley and Blue Mountains
541-969-8200
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