h a l f b a k e r yRIFHMAO
(Rolling in flour, halfbaking my ass off)
add, search, annotate, link, view, overview, recent, by name, random
news, help, about, links, report a problem
browse anonymously,
or get an account
and write.
register,
|
|
|
Microwave ovens heat unevenly. Many solutions have been
proposed <link><link>. These solutions continue the
ineffective and wasteful solution of moving the food about
a bit. These solutions require an oven interior
significantly larger than the object placed within, this is
because ancient
wisdom precludes the movement of large
objects withing small spaces without damage.
So, Move the microwaves, they're lightweight and probably
won't mind. You can do this in two ways: either mount the
magnetron in a fixed position and have a wave-guide with
a raster-scanning mirror. OR, simply tilt the magnetron
around a bit so it sweeps round the interior.
This will mean the end of the turntable, but the writing's
been on the wall for some time. Record and CD players
have lost their once lofty position, even the mighty
spinning-platter hard drive is on the way out.
On the plus side, we'll all be able to put big square plastic
food containers in the microwave without it knocking on
the door like a mournful chimp.
*I'd like to register my disgust at Google Chrome. It's spell
check doesn't recognize "Magnetron".
Waltzing Turntable
Waltzing_20MaGrillDa
[bs0u0155, Sep 26 2013]
Wankel Turntable
Wankel_20Microwave_20Carousel
[bs0u0155, Sep 26 2013]
Microwave oven physics
http://hyperphysics...e/waves/mwoven.html
Wavelength is included in the descriptions. [Vernon, Sep 26 2013]
Please log in.
If you're not logged in,
you can see what this page
looks like, but you will
not be able to add anything.
Annotation:
|
| |
"Stirrer" technology has been around for decades. |
|
| |
Moving the magnetron is problematic. |
|
| |
How do you maintain the coupling between the magnetron, the waveguide and the oven chamber ? Waveguides rely on specific resonant lengths. Change the length of a waveguide and the VSWR will go all to hell (a technical engineering term). |
|
| |
Moving the magnetron requires a flexible high-power coupling between the power supply and the magnetron, a high current low voltage link. But moving the magnetron and its power supply is a lot of mass and bulk so you end up with a big cabinet. |
|
| |
Magnetrons are thermionic devices. They don't like being bumped while they're running. In aircraft, there are elaborate shock-mounts and vibration isolation structures to protect them. Bulky, costs money. |
|
| |
In one sense the fundamental problem, behind the
stuff that [8th of 7] mentioned, is the physical
size of the microwaves. Their wavelength is about
12 centimeters, and the amplitude of a single
photonic wavicle is also that size. |
|
| |
Note, normally "amplitude" refers to things like
"total power level", but that's not what I'm talking
about here. If you want to describe any single
photon as a sine wave, then the difference
between trough and crest, of that sine wave,
always equals the wavelength. (And so
microwaves are simply too "fat" to escape through
the holes in the metal mesh that covers the glass
door of the average microwave oven.) |
|
| |
If microwaves were smaller they would be easier
to manipulate with small parts, as this Idea
describes. But they are what they are, the "right"
size associated with a high absorption rate by
water molecules (and so those molecules acquire
energy and get hotter). |
|
| |
// If you want to describe any single photon as a sine wave, // |
|
| |
We don't. We want to describe it as a particle. |
|
| |
// microwaves are simply too "fat" // |
|
| |
That's totally sizeist, and an appalling thing to say. You should be ashamed of yourself. |
|
| |
// molecules acquire energy and get hotter // |
|
| |
There's a glaring error at the beginning of your link, [Vernon]: |
|
| |
"By federal regulation, microwave ovens are limited to 5 milliwatts (mW) of microwave radiation per square centimeter at approximately 2 inches from the oven surface. This limit is far below the level known to harm people. The microwave radiation would be expected to drop off according to the inverse square law, so at 20 inches it would be down by about a factor of 100." |
|
| |
The inverse square law applies only to point sources. A microwave oven is itself more than 20 inches long. |
|
| |