On 08/24/2016 01:12 PM, rickman wrote:


Perhaps you can explain what the shield does on a receiving loop
antenna? Your explanation clearly says an antenna can be magnetic in
the near field. That is what the term means for receiving antennas. At
lower frequencies much interference is in the near field and is electric
rather than magnetic I am told. Think 100 kHz and household appliances.

The term "magnetic" is usually used in context of a transmitting antenna


Hello, and before we get too far afield, I submit that well-respected
EM/Antenna theory textbooks (e.g. those by Jackson, Stratton,
Kraus,Jasik, Terman) don't use the term "magnetic loop antenna" just as
they don't use "electric dipole" antenna". EEs who design antennas
don't either. Hams seem to coin their own terms but not always for
valid theoretical reasons IMO. EM theory says if we make the area of a
single loop of conductor carrying uniform current very small then it can
be considered to function as a "magnetic dipole". But EM texts would
call this a small loop vice magnetic loop antenna. Likewise we consider
an "electric dipole" to be a straight conductor of very small length
(compared to a wavelength) carrying uniform current.

Finally, it's not my intent to imply one has to have an EE degree to
enjoy ham radio and build and experiment with various types of antennae.
Just like you don't have to understand all the nuances of fluid
dynamics to enjoy sailing or flying an airplane. Sincerely, and 73s
from N4GGO,

--
J. B. Wood e-mail: