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Old April 27th 13, 05:46 PM posted to rec.radio.amateur.antenna
Szczepan Bialek Szczepan Bialek is offline
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First recorded activity by RadioBanter: Oct 2009
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Default Anyone know where I can find plans for an artificial ground?


"W5DXP" napisal w wiadomosci
...
On Friday, April 26, 2013 10:52:18 AM UTC-5, Szczepan Bialek wrote:
The dipole with grounded one leg is quite different from the "symmetrical
dipole".


According to the official IEEE definition of a "dipole", it is any antenna
with approximately the same radiation pattern as a dipole.


Of course: "Dipoles have a radiation pattern, shaped like a toroid
(doughnut) symmetrical about the axis of the dipole. The radiation is
maximum at right angles to the dipole, dropping off to zero on the antenna's
axis. The theoretical maximum gain of a Hertzian dipole is 10 log 1.5 or
1.76 dBi. The maximum theoretical gain of a ?/2-dipole is 10 log 1.64 or
2.15 dBi."

The antenna like this:
http://en.wikipedia.org/wiki/File:Di..._in_meters.png

". However, coax is not symmetrical and thus not a balanced feeder. It is
unbalanced because the outer shield is connected to earth potential at the
other end. When a balanced antenna such as a dipole is fed with an
unbalanced feeder, common mode currents can cause the coax line to radiate
in addition to the antenna itself,[5] and the radiation pattern may be
asymmetrically distorted"

Such antenna is MECHANICALY symmetrical.
But electrically is rather like the Marconi monopole:
http://en.wikipedia.org/wiki/File:A6-3EN.jpg

Remember: The grounded leg is the radial.
S*