[Antennas] RG-178 balun turns count

Fri Jul 2 18:28:41 EDT 2010

de WB2CPN
It's easy for me to understand Common Mode current as it
applies to balanced transmission lines. I mean current which
flows on both wires in phase, but It's not clear how this concept
is transferred to an unbalanced coaxial cable. Incidentally,
for high-voltage power lines common mode current is a no-no.
If there is common mode current flowing in the shield, is there
also an equal current in the same phase flowing on the center
wire? If not, why not. If so, then the current on the center wire
is the sum of the common mode current and the signal current
which is out of phase with the inside of the shield. Huh?
Also, if a coaxial cable is wound around a ferite core, and a
inductance meter is used to measure the inductance of the
center wire, and then the shield, are the values the same?
73 Clete