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Old August 13th 03, 04:52 AM
W5DXP
 
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Yuri Blanarovich wrote:
No standing or laying waves allowed. We are talking about the (mostly)
electrical quarter wave loaded radiators (aka mobile antennas) as used in
shootouts.


Those mobile antennas are standing-wave antennas. The forward current is
relatively constant and is reflected at the end of the whip. The reflected
current adds to the forward current to give the total current. A standing-
wave antenna is similar to a transmission line with standing waves except
that it is designed to radiate and the transmission line is not. The major
reason that the current drops through the loading coil is the same as for
a 1/4WL monopole without a loading coil. The total current is maximum at
the feedpoint and drops to zero at the end of the whip because the forward
and reflected currents add to those values. The forward current through the
coil is virtually the same value at each end of the coil. The reflected
current back through the coil is virtually the same value at each end of
the coil. The phasing between those two currents is what determines the
total current which is indeed different at each end of the coil.
--
73, Cecil http://www.qsl.net/w5dxp



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