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Old April 10th 06, 10:46 PM posted to rec.radio.amateur.antenna
Cecil Moore
 
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Default Current across the antenna loading coil - from scratch

Richard Harrison wrote:
A conductor can lose energy
through dissipation and radiation forever, not just relocate it
temporarily through storage in a reactance.

The dissipation line at the end of a rhombic antenna does not handle the
entire output of the transmitter at its other end. Most of the energy is
already radiated by the time it reaches the dissipation line.


For instance, consider 100 ft. of 50 ohm coax with losses of
3 dB driving a 50 ohm load from a source of 200 watts.

At the source, we have 100 volts at 2 amps. At the load, we
have 70.7 volts at 1.414 amps. The current dropped by exactly
the same amount as the voltage. Hint: The V/I ratio must be
maintained at 50 ohms for flat lines.

Anyone who doesn't understand RF H-field (current) drop in
a lossy transmission line has probably been so seduced by his
lumped circuit model that he thinks the model dictates reality
instead of vice versa.
--
73, Cecil http://www.qsl.net/w5dxp
 
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