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From: dnc@dartvax.UUCP (David Crespo)
Newsgroups: net.physics
Subject: Re:  Passing large amounts of information thru water
Message-ID: <2433@dartvax.UUCP>
Date: Fri, 28-Sep-84 20:12:32 EDT
Article-I.D.: dartvax.2433
Posted: Fri Sep 28 20:12:32 1984
Date-Received: Sun, 30-Sep-84 06:22:31 EDT
References: <13433@sri-arpa.UUCP>, <819@opus.UUCP>
Organization: Dartmouth College
Lines: 49

 
i am curious about how antennae reception works, in
light of the recent discussion on the subject...what 
i guess happens is that the changing field (transmitted)
innduces the electrons in the metal to act as if there



(oopss)
were a voltage, etc., so that the ac current in the radio 
is then the signal. of course, I am not really 
sure how this carries the information, i.e. am not sure
how this gets tied into carrier waves (fm), or how
the tuner (lrc circuit--resonance, ho!) can tell the 
main frequency(oscillations) from the modulations about that
frequency (is the frequency (i.e. 1010WINS on your radio dial)
an average frequency?) , and more to teh point, 
what ARRE the limits on antennae, size, shape, materials, construction,
direction....also, what are the effects of the medium in which
the waves pass...what are the determining factors: conductivity,
dielectricity, resistance, capacitance, inductance, salinity, pH,
law of averages, density, temperature, pressure, (volume?), 
specific gravity, (gee this is fun), reluctance, dissenting opinion, 
homogeneity, reynold's number, young's modulus, serendipity,
esp: salt water vs. fresh, 
i think the thought about the antennae size may have been a 
"misapplication" of the reasoning that comes up around diffraction 
and the relationship between the size of the wave and the object 
(hole in a diffraction grating)... the hole must be about the size of the
wave for diffraction to occur (light as a wave), versus the other
wtwo cases (shadows and insignificance). what is the 
coupling between the electr field and the antennae...is that the question?
 
anyhow....this is all to much, fun, that is, 
 
but for the person out there, wherever you are, looking for 
+ or -i  terms on your feynman graph to propagator terms
in your ahamiltoninan, the following towo books on
field theory and particle physics contains sketches and
derivations of these factors...
first...Introduction to Particle Physics, by Omnes at Orsay
2nd.....Particles and Fields , by Lurie 
 also, there is a recently published book
called something like Quarks and Leptons:an Introduction, but 
author is at best, forthcoming. I mean, i have to go back to where I saw it,
not that it was written before its time, or in vilation of causality,
though that would bne a book indeed apropriately written. 
 
dnc over and out