hello! experience with 802.11x and extreme humidity?

[Darryl Smith]

Microwave ovens use a power output of maybe 800W to excite the water.
Wireless cards operate on something like 1-10 mWatt. There is a bit of a
difference here...

Basically MicroWave ovens use BRUTE FORCE to heat the food. They don't
use the most efficient frequency... But building a microwave oven for 22
GHz is a problem - not because of the cost of generating the signal, but
the cost of keeping the signal enclosed. The door needs to seal much
better in order for energy not to escape...

People bitch about cellphone towers and the energy they emit... Well, a
microwave with a door that does not work properly is much worse... MUCH
worse.

Increasing frequency is one of the best ways to decrese range...
Lowering power works too, but lower frequencies are not as attenuated by
walls...

An interesting asside - cellphones commonly work on 800/900 MHz. There
are curves in the text books for the attenuation of cellphone signals
per mile in a pine forrest, and areas with pine trees. Turns out that
pine trees are the worst thing possible for cellular signals... Their
needles are exactly the right length to create a resonant antenna, and
blocks the signal well...


Even in 100% humidity, most of the air is empty.... Therefore the odds
for attenuation of a signal is poor, since not much signal will hit the
water. 100% water is different since it is a solid, and in a
structure...

Darryl


---------
Darryl Smith, VK2TDS   POBox 169 Ingleburn NSW 2565 Australia
Mobile Number 0412 929 634 [+61 4 12 929 634 International] 
Darryl at radio-active.net.au | www.radio-active.net.au  

-----Original Message-----
From: wireless-admin at lists.samba.org
[mailto:wireless-admin at lists.samba.org] On Behalf Of 'Timothy Murphy'
Sent: Monday, 14 October 2002 12:26 PM
To: Darryl at radio-active.net.au
Cc: wireless at lists.samba.org
Subject: Re: hello! experience with 802.11x and extreme humidity?


On Mon, Oct 14, 2002 at 10:18:35AM +1000, Darryl Smith wrote:
 
> It gives a few references on absorbtion of water at varieous 
> frequencies, and notes that microwave ovens do not work by exciting 
> water molecules, but by twisting both the dipoles in a water atom 
> increasing its kinetic energy.

If 2.4GHz radiation does that to water in a microwave,
won't it do it to water in the air too?

-- 
Timothy Murphy  
e-mail: tim at birdsnest.maths.tcd.ie
tel: 00353-86-233 6090
s-mail: School of Mathematics, Trinity College, Dublin 2, Ireland