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Old October 16th 09, 01:32 AM posted to rec.radio.amateur.homebrew
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First recorded activity by RadioBanter: Apr 2007
Posts: 11
Default The dish problem

raypsi writes:

Hey OM:

Take a 60db gain dish illuminate that with 20 milliwatts of power.
Your ERP is now 20,000 watts.


EIRP, actually ... Radiated power, relative to a (abstract) isotropic
radiator.

My question raises the bar, how can you focus 20 milliwatts of EM
particles and waves, to end up with 20,000 watts of EM particles and
waves?


You can't. You're just focusing that 20 mW of power in the "useful
direction"

Imagine an incandescent light bulb hanging from a wire -- this is a
reasonable metaphor for an isotropic radiator - it puts out (nearly) the
same amount of light in all directions ... If the light isn't bright
enough to read a book, you might put a reflector behind it - there is no
more light being generated, but the page just got brighter, because some
of the energy that was illuminating the garage roof, your head, the
walls and the junk on the shelves is now illuminating the page.

And I can bet that it's all those extra particles that are
going to be cooking my turkey.


There are no particles, and there are no "extra" particles.

de n8zu

It comes from "focusing" the existing energy. No new energy is created.

Yes, you *could* do that with a turkey. Just like you *could* cook it
with a magnifying glass out in the sun.


Indeed - first you heat one molecule of water, then refocus the beam,
heat the next, repeat 6 x 10**23 times for each mole of turkey.


-Bill

 
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