hello! experience with 802.11x and extreme humidity?

[Darryl Smith]

>Both DECT phones and GSM phones use this frequency range without
apparent interference 
>from microwave ovens. I've never noticed any interference with WiFi
from these ovens.

That is because these operate well off frequency. 
	GSM:	900 MHz, 1800 MHz, 1900 MHz
	DECT: 1880 MHz to 1900 MHz

	Microwave Oven: 2400 MHz
	Bluetooth: 2400 MHz
	802.11: 2400 MHz

The attenuation of water at 2400 MHz is higher than 900 MHz and 1800
MHz, but not too bad. There are absorbtion graphs that should be looked
at and you will see that until the higher absorbtion frequency.

There should be no interference between microwave ovens and 802.11 since
the oven is supposed to contain all the radiation. But it will
interfere. So will bluetooth. Bluetooth is worse (and I believe should
be banned :-)...

As for why 2.4 GHz... Well, the argument that 433 MHz cannot support
large range communications is false, and it is also ISM. There are ISM
bands all over the place, there fore various applications. 2.4 GHz was
the best for wireless lan since it provided the best trade off between
range and bandwidth.

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 9:00 AM
To: chris.hill at crhtelnet.com.au
Cc: wireless at lists.samba.org
Subject: Re: hello! experience with 802.11x and extreme humidity?


On Sun, Oct 13, 2002 at 09:10:19PM +0800, Chris Hill wrote:
 
> Why do you say that 2.4GHz is a resonance frequency of water?  It's 
> not. For a basic starter, see : 
> http://howthingswork.virginia.edu/microwave_ovens.html

I found this article quite interesting,
but very unconvincing on one point.
The author says 
"Since leakage from these ovens 
makes the radio spectrum near 2.45GHz unusable for communications, the
frequency was chosen in part because it would not interfere 
with existing communication systems."

Both DECT phones and GSM phones use this frequency range without
apparent interference from microwave ovens. I've never noticed any
interference with WiFi from these ovens.

I've certainly always understood that 2.4GHz was alloted to ISM because
it was unsuitable for long-range wireless communication on account of
some interaction with something in the atmosphere.





-- 
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