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Old August 30th 10, 11:44 AM posted to rec.radio.amateur.antenna
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Default Whip antennas with coils

On Aug 29, 10:38*pm, Roy Lewallen wrote:

Difficulty in getting power to an antenna is due to the mismatch between
the transmitter and the impedance it sees, rather than between the
transmission line and antenna.

As a simple example, consider a 75 ohm dipole connected to a transmitter
through a half wavelength of 600 ohm transmission line. /etc


Rather than using an example of a balanced antenna having reasonably
high radiation resistance and zero or low reactance at its input
terminals, let us consider a base-fed 10 foot whip at 3.8 MHz -- which
is more along the lines of this thread.

Without using a loading coil, the input Z of that whip is about 0.6 -j
1250 ohms. The SWR that this antenna input Z presents to unmatched 50
to 600 ohm transmission line ranges from 52,167:1 to 5,340:1.

Not much power will be transferred through such a match, which is the
reason for the statements in my quote which you referred to.

RF
 
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