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Old March 8th 06, 07:18 PM posted to rec.radio.amateur.antenna
Roy Lewallen
 
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Default Vertical vs Horizontal shootout part one

Michael Coslo wrote:
Okay. Perhaps I might better characterize my experiment as a
comparison of a vertical and an OCF dipole of indeterminate vertical vs
horizontal performance. I was under the impression from the designers of
this flavor of dipole that they were not radiating from the feedline
unless you wanted that "feature".


Unfortunately, even if the designers don't intend the feedline to
radiate, it's very difficult to avoid. A single balun at the feedpoint
is very likely not enough to prevent it.

In that case you would feed the
antenna with balanced line.


That would make no difference at all in determining whether or not the
line would radiate.

Certainly the antenna doesn't seem to be
radiating RF from anywhere but the antenna bits.


The amount of feedline common mode current and therefore radiation will
vary from band to band, probably a great deal. It's easy enough to make
up a simple current probe with a clamp-on core and make quantitative
measurements if you're interested. They've been described on this
newsgroup several times.

Roy Lewallen, W7EL