"Richard Clark" wrote in message
...
On Thu, 22 Jan 2009 01:06:28 -0000, "christofire"
wrote:

With a pair of screened loops and a whip it is possible to receive
separately the magnetic and electric fields associated with a radio signal
and to record their strengths at different locations. This can reveal
significant differences on account of building and electrical clutter, but
only if the loop is adequately screened. No myth!

What you describe is a direction finding system with a general antenna
that can be switched in to sniff for a transmitter to take a bearing
on. A commonplace design for this application.

No, the loops were commutated in order to provide an omni-direction pattern
in the horizontal plane and the receiver was switched between the loops and
whip to measure H and E. This was used to establish for medium and
long-wave broadcasting stations (in the UK) the field strength and
receivability on ferrite-rod antennas.

The loops are no more
screened than any other, and careful observation of their construction
details would reveal the necessary break in the screen which serves
for balance only.

The loop has to be split at some point to prevent it acting as a shorted
turn - the splits were at the top in this case.

Any claims to magnetic field separation are, as
Mark well put it, a myth.

The only way you could achieve this separation is by traveling at the
speed of light with your antenna in that magnetic field, at its 90
degree peak to the electric field null.

In a normal single, plane-polarised, far-field TEM radio wave the peaks of E
and H occur at the same places and the same times, and the nulls of E and H
occur at the same places and the same times. The peaks of both correspond
to the peaks of current in the transmitting antenna by which they were
generated, and the nulls of both correspond to the zero-crossings of the
current. If you believe something is radiated in the far field when the
current in the antenna is zero I would be intrigued to hear an explanation.

This reduces the topic from
the status of myth to that of absurd.

You're entitled to your opinion.

Chris


73's
Richard Clark, KB7QHC