"NM5K" napisal w wiadomosci
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On 6/13/2012 5:11 PM, garyr wrote:
This site http://www.frontiernet.net/~jadale/Loop.htm states that: "A
properly designed Loop primarily responds to the magnetic component of
the
radio wave. Note that noise resides primarily in the electrical
component..."

Whereas this site shows that that is not the case:
http://vk1od.net/antenna/shieldedloop.

"The operation of the shielded loop is explained popularly by first stating
that the desired loop current is due to the magnetic field, and then
maintaining that the metal shield cannot be penetrated by the electric field
but can be penetrated by the magnetic field. All these arguments are
incorrect in the light of fundamental electromagnetic principles."

So what is the advantage, if any, of a shielded loop antanna?

None. The only purpose is to ensure balance, which helps give
deeper nulls.

But that is not the only way to ensure balance. A shield is
not required for that function.
None of my AM-BC loops are shielded. I have tried shielded
loops though, just to see for myself if any difference.

Do you use them to the "direction finding"?

"The advantage of this feed arrangement is that the coaxial feed typically
enters the loop opposite to the gap, and if attention is paid to symmetry of
the loop and feed, the balance that is achieved. Best balance yields the
deepest null which is important in direction finding applications for
instance."
S*

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