[TowerTalk] wire antennas

[Darrel Van Buer]

The National Electrical Code specifies wire size for antennas (I realize the US NEC does not
apply to ON land), though the concern in the NEC is mostly mechanical - i.e. it will stay up, 
not fall and give someone an RF burn or electrical shock.

The NEC recognizes 3 categories:

Receive only antenna up to 35 feet: #18 hard drawn copper or copper clad steel.
Antenna with under 150 feet long span: #14 "
Antenna over 150 feet: #12                 "

While I have put antennas that don't meet these guidelines, they also tended to break within
a few years.  

>From the point of view of losses, even #24 would only take 5 or 10% off
efficiency for an 80m dipole.  Legal limit power in a 50 ohm antenna would be under 6 amps
which would require #18 to #20 in an extension cord, but a wire in free air has less heat
problems than bundled or in conduit so somewhat smaller wire would still stay cool enough.

	Darrel AK6I

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