On 20 Oct 2004 12:51:58 -0700,
(E-Mail Removed) (Joe) wrote:
>I am attempting to assemble a wireless network in a wooded area
>(campground aprox 1 mile radius) where campers would be able to have
>internet access.
Trees and 2.4Ghz do not mix. Broadleaf trees and trunks are like a
solid wall. Nothing gets through. Needles and light foliage might
work.
>I am looking for some possible solutions without
>running any cabling.
You might wanna look into wireless repeaters and WDS (wireless
distribution something). They eliminate the wired backhauls, but cut
your effective bandwidth in half.
>I also have a few buildings I would like to tie
>into the system.
How far away?
>I currently have a cisco 350 access point, some workgroup bridges,
>some 14dB gain amps, and a 15 dBi gain omni antenna.
Loose the amps. They cause more trouble than they're worth. Also,
you're going to be illegal if you use the amp with that setup.
Maximum into an omni is +30dBm (1 watt) into a 6dBi omni for a grand
total of +36dBm EIRP.
http://www.wi-fiplanet.com/tutorials...le.php/1428941
If you start with the +20dBm from the Cisco AP you'll be overdriving
the +14dB amplifier, which would allegedly be putting out +34dBm or
about 3 watts. My guess is your unspecified amplifier puts out no
more than 1 watt (+30dBm). Therefore, you'll need to add -4dB of
attenuation to use the amp effectively and limit your antenna gain to
6dBi. If you use the 15dBi omni antenna, you're way over the legal
limit.
With the +15dBi antenna and the +20dBm output Cisco 350, you're 1dB
below the absolute max EIRP limit.
>What height would be optimal for the antenna?
Any reason why you didn't bother to specify the make and model so I
can lookup the vertical radiation angle and downtilt? This is a
serious problem with high gain vertical omni antennas. The vertical
radiation angle can easily be so narrow that if you mount the antenna
too high, you end up sending all the signal over everyone's head.
Even so, you will also have very little signal directly below the
antenna.
http://www.ydi.com/calculation/downtilt-cover.php
Typical for a decent 15dBi omni is 3 degree beamwidth (-3dB) and 3
degree downtilt. That's a mighty narrow beamwidth. You may have to
put it almost at ground level in order to make it work.
>Am I going to need to
>get more access points to use as repeaters or is there a better way of
>doing this?
IMHO, repeaters and WDS doth suck. A better idea. Find a tree that
overlooks the campgrounds from the edge, not the center. Dump the
omni and replace it with a 8dBi panel or 120 degree sector antenna.
Point the panel antenna downward toward the campground. Keep the
antenna below the branch level to avoid tree cluttter. There's less
of that low to the ground. Use a 2nd radio, on a different channel,
to act as a transparent bridge to act as a backhaul to wherever.
>Any suggestions would be greatly appreciated.
--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831.336.2558 voice
http://www.LearnByDestroying.com
#
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