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Re: Microwave Oven at 2450 Mhz



Dave G. wrote:

>I was in my local DIY store this afternoon, looking to upgrade 
>my very old microwave oven...
>Looked inside a particular unit to see what power it was 
>running,
>The label said "1.2kW at 2450 MHz"
>What would that do to my prospects of working Echo, et. al. if 
>I bought it ????
>  
>
What frequency do you think the old oven operates at?  ;-)

At that frequency the H2O molecules in water form attempt to rotate/move 
to align with the polarity of the changing fields in the nice Faraday 
cage they built there for you, and in so-doing, rub/bang against each 
other, creating friction that heats your food.  Other molecules in the 
food also do this, but not as rapidly as water.  Most food has plenty of 
water in it and rubbing all the molecules of water rapidly against each 
other is a pretty smart way to heat up your Hungry Man Dinner.

There's a lot of bad information out there that states that water 
"resonates" at 2.4 GHz, but it's not really true.  The water molecule 
turns RF energy around that frequency directly to internal molecular 
motion, is all. Scientists say the motion is more like a "rotation" than 
motion, really... the shape of the H2O molecule allows it to "twist" 
along a couple of axes, to a point.  And I'm no scientist... so Your 
Mileage May Vary.

The use of 2.45 GHz for most microwave ovens is just a side-effect of 
the frequencies available for "industrial" use at the time of the 
creation of the first ovens.  2.3 GHz or 2.6 GHz would work just as 
well, but the FCC would have been grumpy with the manufacturers.  From 
what I've read, anyway.

For those with deathwishes, there's always the Unwise Microwave Oven 
Experiments web page:
http://www.amasci.com/weird/microexp.html

[There's a ton of these websites on the Net, this is just one I had 
bookmarked.]

The TV show Mythbusters also did an entertaining little bit on microwave 
oven myths.  Their little segment on superheated water was 
entertaining... boom.

Easiest solution to any QRM problem if any of the energy is leaking out 
of the oven?  Just make the popcorn and heat up the coffee before you 
fire up the rig and  start calling CQ!  Hopefully your oven is not 
leaking that badly, or you have other problems to deal with!

If you have played with 802.11 variants, you can see that some of the 
manufacturers include an error-corrected mode that supposedly "protects" 
your wireless data network from "microwave oven interference".  I've had 
the wireless laptop sitting next to the microwave oven numerous times 
and never experienced this so-called "problem", making me think that 
someone out there is either great at silly marketing, or there's a lot 
of really leaky ovens around!

Nate WY0X
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