[Antennas] Faraday Loop construction question.

[Terry Conboy]

At 08:29 AM 2007-08-20, Sam Morgan KA5OAI wrote:
>I have a question on constructing a faraday loop using the 
>http://www.qsl.net/mnqrp/Loop/Mag_Loops.htm
>image of the faraday loop http://www.qsl.net/mnqrp/Loop/Pickup%20Loop.gif
>
>Is that faraday loop of RG8 cut completely through on the far side?
>
>and then the outer jacket stripped back on one side exposing the shield
>and on the other side you strip back the outer jacket, and the 
>shield exposing the center conductor
>then you solder the center conductor to the exposed shield on the 
>other side of the gap?
>
>the reason I ask is a friend has been told you don't cut center 
>conductor some how.......
>I can't even figure out what he is being told.....?

The center conductor is connected to the outer shield of the left 
side of the loop at the midpoint (at the point opposite the feedline).

The other end of the shield on the left side is connected only to the 
outside of the shield of the feedline.

The center conductor inside the left side of the loop need not be 
connected to anything (and could even be removed, so obviously, it is cut).

The shield on the right side (at the midpoint) is open circuit (so it 
is cut, too.)

The current from the center conductor of the feedline flows on the 
outer part of the shield on the left side.
The current from the inside of the shield of the feedline flows on 
the outer part of the shield on the right side.
This makes for a reasonably well balanced coupling loop.

BTW, the description of small loops as only responding to the 
magnetic field is folklore.  See 
http://www.w8ji.com/magnetic_receiving_loops.htm for more accurate 
info (although W8JI doesn't discuss the coupling loop itself).

73, Terry N6RY