[MLB-WIRELESS] 2.4GHz through obstructions (WAS: Colorbond/roof insulation interference.)
pickle at alien.net.au
Tue Feb 18 08:25:17 EST 2003
> Anyone know if you can take the attenuation of the colorbond
> into account in EIRP calculations?
My research from about 8 months ago dug up a little table (included
below), which isn't very specific. I was looking at pushing signals
through things like roof-tops, or corners of buildings at the time, and
compiled the list from googling many sites. Personally, I wouldn't rely
on it entirely, but it's been decent enough to make eye-ball judgements
IMHO (I try to obtain an SOM of > 18 dB).
If anyone can confirm or provide more accurate details, maybe this would
make a useful wiki page somewhere. I get a lot of friends asking whether
they'd be able to go through a neighbour's roof, and so forth.
Unfortunately, I didn't get any info for trees, sorry..
Obstruction | Attenuation
Bessa-Block | 4 dB
Brick | 3 dB
Door (Metal) | 12 dB
Door (Wood, solid) | 4 dB
Door (Wood, hollow panelled) | 3 dB
Glass | 2 dB
Glass (Wire-Mesh security) | 9 dB
Gyprock plaster; metal frame | 7 dB
Gyprock plaster; wooden frame | 5 dB
Limestone | 5 dB
Roof (Corrugated Iron) | 14 dB
Roof (Flat metal) | 12 dB
Roof (Tiled; Dry) | 5 dB
Roof (Tiled; Wet) | 11 dB
Wooden wall | 8 dB
I think a corrugated iron/BHP Colourbond style roof, with an antenna
inside, would act more like a reflector, bouncing the signal downwards,
although in all sorts of wonky directions due to the corrugations.
I'm no expert, though, just someone with too much time on his hands this
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