(E-Mail Removed) (Rico) hath wroth:
>Basically as others will tell you, 2.4 GHz signals don't pass through
>walls. What happens is the signal bounces around and or finds a 'hole' in
>the wall. Thicker the wall the less likely of finding enough of a hole to
>make the trip.
>Consider one of the devices that allows networking on your power lines
>already wire in the house or the phone wiring.
Generally true for most common construction techniques. Wireless
really does bounce around and find a suitable hole, usually a doorway.
However, it can only bounce a limited number of times before multipath
and path length extension become a problem.
Drivel: One of my fun projects many years ago was trying to figure
out how many walls and floors could be penetrated by 2.4Ghz Wi-Fi in
an office building. One wall was easy. Two walls were a bit of a
challenge. Three walls resulted in a rather weak and unusable signal.
But as we added more and more walls and floors, the signal continued
to be present at almost the same level. We eventually found about 8
walls had almost exactly the same weak and unusable signal level as 3
walls. It didn't just fade away or disappear as one would expect.
What was happening was the signal was going out the window, was
reflected off a nearby building, and re-entered via another window.
Different signals have different attenuations. RF will go through
most common materials with varying attenuations. As a rule of thumb,
6dB loss is 1/2 of the range. 12dB loss is 1/4th the range. This
means if you put a plywood wall between the AP and the client, a 6dB
loss through the plywood will results in 1/2 the range that would be
obtained without the plywood obstruction. My guess(tm) is anything
over about 12dB attenuation is going to be unreliable or flaky.
I did a survey of various web sites and books claiming to have
measured or calculated the attenuation of various materials. See:
|
http://www.thirdbreak.org/pipermail/...ne/000804.html
Note the wide variation in opinions and measurements. I don't agree
with all the numbers.
Dumb story: Descriptions also vary. One client asked me to improve
their office indoor coverage. They described the office as having
very light weight partitions, with very little metal in them. I
expected to find a radio or interference problem. Instead, I found
row after row of metal file cabinets and blueprint storage cabinets
propped up against both sides of the office partitions. I apparently
forgot to ask about office furniture. I gave up immediately and just
two more access points on opposite sides of the offending partitions.
--
Jeff Liebermann
(E-Mail Removed)
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558