[MLB-WIRELESS] 2.4GHz through obstructions (WAS: Colorbond/roof insulation interference.)

Simon Butcher pickle at alien.net.au
Tue Feb 18 08:25:17 EST 2003

Hi :)

> 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
morning :)


 - Simon

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