On Sep 13, 12:47*pm, Roy Lewallen wrote:
The difficulty with having common mode current on one side of an
"isolator" or common mode choke (current balun) is that it creates a
field which couples to the line on the other side, generating a common
mode current on the other side.

Since I don't know how robust the Carolina Windom isolator is, my
following statement may or may not apply to the Carolina Windom.

The above problem goes away *if* the choking impedance is high enough
to *cause* a common-mode standing-wave current node (minimum) at the
choke because the net magnetic field is then near zero on both sides.
The same thing happens when a well-designed trap is placed in a
dipole. The high impedance of the trap at the parallel resonant
frequency causes a standing-wave current node and reflects the forward
wave back toward the feedpoint instead of allowing current to flow
through it into the rest of the wire. Here's the current distribution
on a trapped antenna. Note how the trap impedance causes a standing
wave current node at the trap.

http://www.w5dxp.com/trap.JPG
--
73, Cecil, w5dxp.com