wrote in message
...
On Jan 22, 6:32 am, Cecil Moore wrote:


I'm not talking about coaxial loops. I'm talking about
coils of wire wrapped around a ferrite rod typical of
AM radios. Seems pretty obvious it is responding to the
magnetic field when it needs to be at right angles to
the transmitting monopole (or dipole).
--
73, Cecil http://www.w5dxp.com

I don't see how you could be receiving the magnetic
field if say you are 150 miles away from the station.
I looked around on the web for other opinions, and
ran across a page from W8JI.
http://www.w8ji.com/magnetic_receiving_loops.htm
I tend to agree with him.
Here is one quote that seems to fairly well explain
the position.

From W8JI web page..
"Acceleration of charges causes a very unique force
on other charges in the Universe. We call this effect
electromagnetic radiation. It is a totally different effect,
and it is independent of induction fields. This is the only
effect or force that works to move charges at a very
large distance, and it cannot be created by mixing
induction fields. "

Anyway, that's about as good an explanation as I
can find as to why I don't believe in "magnetic" antennas,
except for the properties at very close distances.
At any greater distance beyond about 1/10 wavelength,
it all goes out the window.
That's the way I see it on January 22, 2009 at 7:55 in
the PM. :/


Could I suggest taking a look at one of the well regarded text books such as
'Antennas' by J. Kraus. Your local library may be able to get it in for
you. There you'll find it well explained that 'electromagnetic radiation',
a radio wave, has associated with it an electric field and a magnetic field.
Each is measurable and is a manifestation of the radio wave - it's probably
incorrect to say, the other way round, that the radio wave is formed by the
'radiation' E and H fields. Drawing power from a radio wave in order to
operate a radio receiver can be done using either an antenna sensitive to
the local E field strength, such as a whip or many types of wire antennas,
or using an antenna sensitive to the local H field strength, such as a
loop - i.e. a magnetic antenna. It may be argued that either would have
some effect on the other field, but this may not be very important in
practice.

These radiation fields alternate in time with one another, in sync with the
current in the antenna, but the phase of their alternation is (obviously)
retarded with distance away from the antenna - because of the limited speed
of propagation of a radio wave. They are directed transverse to the
direction of propagation and are oriented perpendicularly to one another in
that transverse plane.

'Induction' and 'electrostatic' reactive fields are found close to a
transmitting antenna, but these decay with the square or cube of the
distance and at distances greater than wavelength/2*Pi they are weaker than
the radiation field.

I hope this helps a bit.

Chris