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Old March 6th 08, 12:07 PM posted to rec.radio.amateur.antenna
Richard Fry Richard Fry is offline
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First recorded activity by RadioBanter: Jun 2006
Posts: 440
Default 'SMALL' ANTENNA CRITERIA

wrote:
I agree. I think it's quite possible that even a decoupled feedline
will add enough radiation to make the antenna noticeably better
than it really is. I'd prefer to see the source mounted *at* the
antenna to make it a decent comparison.

__________

Unless this antenna is itself balanced, most likely for best efficiency when
operating in this configuration there would need to be a conductor running
from the elevated tx chassis to a good r-f ground of some kind, either
buried in the earth or in the form of a counterpoise. Radiation from that
"ground" conductor could be many times greater than from what is considered
to be the antenna -- even though no feedline is present..

This is a common configuration used for so-called Part 15 AM installations
to get greater groundwave coverage from the 100 mW tx input power allowed
under FCC Part 15.219, by ignoring the 3-meter limit on the length of the
radiating structure given there.

RF