Topband: QST Jun 06 RX Loop

Donald Chester k4kyv at
Thu May 18 20:02:49 EDT 2006

>From: "Richard (Rick) Karlquist" <richard at>

> > Place ferrite beads over the ends of the shield adjacent to the
> > shield gap.
> > You will now find that the shielded loop no longer receives anything.
> > What happened to the shield's permeable magnetic coupling to the center
> > wire?  Could it be that currents on the shield's surface were travelling
> > around the end of the gap to enter the inside of the shield and
> > then couple
> > to the center wire?

So, why couldn't that same principle be used to cancel the pickup from the 
vertical downlead of a Beverage antenna?  Just use a piece of coax for the 
downlead.  Ground the shield at the bottom, and place ferrite beads over the 
end of the shield at the top, where the centre conductor comes out to 
connect to the Beverage wire.

>Explanation:  the ferrite beads are also surrounding the inner "antenna".
>So that "explains" why it goes dead.

If that is the case, then the Beverage should go dead when the ferrite beads 
are installed..

Don k4kyv


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