Hm. That means that you can't run more than about 16-20 watts to an
ordinary dipole, since a dipole over ground produces a field strength
that's typically 4-5 dB greater than a dipole in free space. See, for
example, the EZNEC example BYDipole.EZ, which shows a field strength of
6.82 dBi, or about 4.7 dB greater than a free space dipole.

Roy Lewallen, W7EL

Greg Queen wrote:
Cecil,

I am no expert on the "legalese", but it appears the FCC has specified power
in terms of Effective Radiated Power (ERP). The standard is no more than
50-watts radiated by a dipole in free space. My interpretation is that you
look at the performance of your antenna at its maximum radiation point
(i.e., the azimuth & elevation) and compare it to the radiation from a
dipole in free space at its maximum radiation point(s). If your antenna has
less radiated power than the dipole, then you can feed more power to the
antenna (up to the point that you get the same radiation as a dipole in free
space).

I think this is the first time the FCC has used ERP (which includes antenna
gain and feedline loss) as a power specification for amateur radio.

Greg Queen
AE6MF