Owen Duffy wrote:
The current that flows on the outside of the coax outer conductor is
I1+I2.

It appears to me that the two currents are designed
to create a transmission line stub in the middle of
an antenna wire. What if I2 is equal in magnitude
to I1 and phase-shifted by 180 degrees? Wouldn't
that cause all the current to flow *inside* the coax
thus eliminating common-mode currents at the trap?
If common-mode currents are eliminated at 'A', wouldn't
that also eliminate common-mode currents at 'B'?
--
73, Cecil http://www.w5dxp.com