Apollo,
1. With 200mW = 23dBm you can use a 13dBm antenna to stay within FCC
limits with it being point-to-multipoint.
2. Studies from Bell Labs a.k.a. Lucent and others have shown that
horizontal polarization in buildings can increase
your range by up to 10 times the range you would get from vertical
polarization. This is due to the fact that walls
are generally thinner than the floors and therefore signals bounce
off of the floors more than the walls. This gives
you a horizontal corridor. With that being said, I am still skeptical
of it covering the whole building.
3. If you use a 120 degree sector antenna you can form a triangle with 2
sides equal for math purposes. If you divide
that into 2 right triangles then they are usable to determine your
coverage. Since it is 80 feet from the building
you can use some trig to figure out how wide your signal will be at
the edge of the building.
60deg /|\ <-- Not to Scale
/ | \
/ 8|0 \
30deg /___|___\
Tangent = opposite / adjacent
tan 30 = 80 / x
.58 = 80 / x
x = 80 / .58
x = 138.56
Since that is only half of your coverage you need to double that so you
get a coverage that is approximately 277 feet wide at 80 feet from your
120deg sector antenna.
So a 120deg sector antenna will cover an extra 50ft on each side of your
170ft wide building.
So what angle should you use?
angle A/|\ <-- Not to Scale
/ | \
/ 8|0 \
/___|___\
85ft
tan A = 85 / 80
cotan (85 / 80) = A
A = 46.8
Again double that and you get 93.5 degrees.
You might be safe using a 90 deg sector antenna but a little over would
be a little better.
If cost matters, a 13dBm 90deg antenna will be a lot cheaper than a
13dBm 120deg antenna.
Hope that helps.
Thanks,
Rodney Milam
Infinite Technologies Group, Inc.
www.ItsInfinite.com
Original Message:
------------------------------
Message: 4
Date: Wed, 14 Apr 2004 13:38:50 -0500
From: "Apollo (Carmel Entertainment)" <[EMAIL PROTECTED]>
Subject: [BAWUG] What dBi 120deg. sector can I use legally w/ 200mW
AP? Some other questions too.
To: [EMAIL PROTECTED]
Cc: [EMAIL PROTECTED], [EMAIL PROTECTED]
Message-ID: <[EMAIL PROTECTED]>
Content-Type: text/plain; charset=ISO-8859-1
I am still in design stage of our non-profit apartment complex wireless
project. Questions I have are:
1. What is the highest dBi 120deg. sector can I use with uamplified
200mW access point without breaking the law?
2. I wonder if I would be able to penetrate our stucture, so I could
serve the units on the other side of the building without doing any APs
on the other side (the light poles there belong to the city). What
polarization should I use?
3. Is one 120deg sector enough to cover a building that is about 80feet
away from building that is 64'deep, 72'high, and 170'wide (and needs to
be covered corner to corner)?
Here is what needs to be penetrated (building is basicly 6 floors of
open style
lofts):
200mW AP (in center of courtyard placed 12' high on the light pole)
120deg. sector
/ \
/ \
/ \
/ 80' \
/to the wall\
___________________(Brick wall with large windows)
29' to next drywall
___________________
6' to next drywall (this is hallway)
----------------------
29' to next brick wall
____________________
I have an satelite image of our property with boundaries and light poles
marked on it. Check it out.
http://carmelme.com/fileadmin/pics/temp/satimage.jpg
Any ideas and advice would be greatly appreciated!
Thanks,
Apollo
-------------------------------------------------
_______________________________________________
BAWUG's general wireless chat mailing list
[unsubscribe] http://lists.bawug.org/mailman/listinfo/wireless
