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Old June 19th 12, 11:35 AM posted to rec.radio.amateur.antenna
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Posts: 52
Default loop antennas

On 06/14/2012 08:12 AM, Wimpie wrote:


The time varying magnetic field generates an electric field and that is
received by the loop. When you screen it completely, it doesn't work,
you need the gap.


Hello, and one more (and final) time: Electric and magnetic fields by
themselves don't propagate, only electromagnetic fields (EM) can
transport energy over vast distances. A transmitting antenna has LOCAL
(near) electric and magnetic fields but what propagates (i.e. what a
receiving antenna sees as the far-field) is an EM field. A receiving
antenna has an "effective area" that captures energy in the incident EM
wave; what isn't dissipated in the load at the receiving antenna
terminals is reflected (scattered) by the antenna (after allowing for
any dissipative/ohmic losses in the antenna structure).

As economics professor Peter Morici would say "It isn't all that
complicated." (But the devil's in the details). Sincerely and 73s from
N4GGO,


--
J. B. Wood e-mail:


 
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