Hi Dieter,
In a message dated 96-10-09 10:34:00 EDT, you write:
>
>Reading a story in a german amateur radio magazine about a "big" 80m
magnetic
>loop from Karl DL1VU gave me an idea of a small topband antenna with the
>possibility of working DX. Well, Karl reported to have worked VK6HD with
this
>antenna and 100W on 80 Meters.. so it can't be too bad.
All antennas are electromagnetic radiators and absorbers, except in very
close proximity to (some areas of) the antenna. In the very close near field
antennas can have direct coupling favoring one form over another, but it is
also accompanied by the other field to some extent.
The signals we talk to each other with are not magnetic, and noise is not
electric. I hope we do not forget this, because noise from power lines and
electrical devices is ALSO an electromagnetic wave just like the signals we
desire. Losses and displacement currents in the earth are caused by magnetic
coupling as well as electric coupling. It is impossible to have a time
varying magnetic field without an accompanying varying electric field, or
vice versa.
>Also you have to use a good conducting and thick wire. I think of coax
shield
>from RG 213 or so.
Woven braid has several times the RF resistance of a similar size smooth
non-braided conductor. A flat conductor is more resistive than the same
surface area round conductor. Keep that in mind when working with RF or
lightning!
73 Tom
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