Thread: Baluns?
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Old September 3rd 08, 12:18 PM posted to rec.radio.amateur.antenna
Cecil Moore[_2_] Cecil Moore[_2_] is offline
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First recorded activity by RadioBanter: Mar 2007
Posts: 3,521
Default Baluns?
wrote:
For a balanced transmission line, the characteristic impedance is not
expressed in differential mode terms, it IS common mode so I do
not know why you ask about differential mode characteristic impedance.

Well, there's your problem. In a properly functioning
transmission line, whether balanced or unbalanced, the
currents in the two conductors are differential, not
common-mode. The two currents are equal in magnitude
and 180 degrees out of phase and their fields tend
to cancel which minimizes radiation.

Common-mode currents only occur when the two currents
are not perfectly differential, i.e. not equal amplitudes
and/or not 180 degrees out of phase.
--
73, Cecil http://www.w5dxp.com
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