Getting into the calculus level of explaining radiation at this point. Also
at the point where ordinary conversational meanings of words diverge from
"specialty" meanings, and technical conversations cease to inform anyone
except those privy to the set of specialty meanings...
The propagation of charge along a line conductor occurs at a fixed
percentage of the speed of light related to physical surrounds (velocity
factor) so the everyday understanding of acceleration (gradually moving
faster and faster) does not apply. It's more like the count of electrons
jumping from steady to moving to the next hole then steadying, then jumping
to moving etc. Radiation is then related to a complex (time + 3D) calculus
add of all the jumps. When the jumps occur in a pattern, then there is what
we would call a discreet radiated signal. If they do not occur in a
pattern, we call it noise.
As I recall, at ordinary non-destructive current levels, the percentage of
electrons moving from atom to atom is a very small percentage of the total
electrons, so the movement is from hole to hole. Jump from orbit, drop into
an empty orbit, "rest". Start, stop, rest. These are very predictable
journeys as the density of atoms in a solid conductor is essentially fixed
by the temperature. Current is the count of these journeys that occur in
pattern.
Higher voltage does not make electrons move faster in ordinary current, it
makes more electrons move at the same speed. It is entirely possible at some
levels of current (received signal levels), that an electron may move just
once during a cycle from the signal we are interested in. The everyday
understanding of acceleration does fit not well when we are mentally giving
that electron a name, social security number, smiley face, putting it in a
car, following its journey up and down the wire, and reading
its speedometer.
DC current is the same string of flips except the count is maintained, and
the vector summary is constant. Since the magnetic field can be detected at
a distance it is difficult to say that it was not "radiated", unless one
uses a restrictive definition of "radiated".
73, Guy.
----- Original Message -----
From: "Andy Wade" <andy@ajwade.co.uk>
To: <antennaware@contesting.com>
Sent: Monday, February 16, 2009 4:46 AM
Subject: Re: [Antennaware] Electrons
> At 16:25 15/02/2009, Guy Olinger, K2AV wrote:
>
>>The often quoted rule: Movement of charge creates electromagnetic
>>radiation.
>
> Surely it's the *acceleration* of charge that causes E-M
> radiation. Movement of charge carriers at constant velocity - steady
> DC - will only set up a constant magnetic (near) field.
>
> 73 de G4AJW
>
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> Antennaware@contesting.com
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