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uwave antenna question: ways to emit 2.45GHz for heat - RF Cafe
Forums
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| ProfK
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Post subject: uwave antenna question: ways to emit 2.45GHz for heat
Posted: Mon Feb 07, 2005 2:14 am
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as a novice to RF, I am confused about antenna behavior
and practical differences among types. There is
a waveguide to a feedhorn, there is waveguide to
coax to something... dipole or the like, heard about
notch antenna whatever that is, transmission lines
and even dishes like for radar. How might these
different antennas allow me to blast microwaves
at something to make it hot? Issues are directionality
and power transfer efficiency AFAIK. Assume we start
with a magnetron.
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Amana |
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Post subject:
Posted: Mon Feb 07, 2005 12:56 pm
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Pretty simple, really. 1) Use directional
antenna like parabolic. 2) Match impedance
of antenna to object to be "heated" in the near-field
(forget far-field for reasonable power levels).
3) Match power amplifier output to antenna input
impedance. 4) Turn on power switch.
5) Cook to your preference (a little darker
to kill mad cow virus).
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Guest |
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Post subject:
Posted: Tue Feb 08, 2005 2:55 am
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Sounds well and good but your plan requires a different
antenna for each item to get cooked. Besides, how
do you calculate the impedence of a rock or a brick?
Wouldn't it change depending on volume too?
Also,
if using a surplus oven magnetron, there is no tuning
possible AFAIK.
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Guest |
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Post subject:
Posted: Sun May 29, 2005 5:42 am
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I certainly hope I am not too late on this, but
PLEASE BE CAREFUL! do not operate the device unless
cleared away. No microwave oven magnetron is safe
enough to operate in open field without getting
clearance of at least 30 feet.
Please ensure
your safety first!
One more thing,
What gets hot in an oven, is what contains
water.
Water gets tuned in 2.4 GHZ, and friction
of the ringing molecules mates it heat.
any
sat dish larger than 1.2m would be sufficien enough
(angle of main lobe ~20 deg. @ 2400 for -6db, but
remember you'll be spreading 100's of watts ERP
in an angle of about 100deg. from the center.
I also estimate about 20 - 40 Watt leakage from
the feed mounting arm, which will finally end up
spreading all over the place...
Do you really
need to do this?!?
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Posted 11/12/2012
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