[Lowfer] Part 15 power limit for Hifers

[Garry Hess]

I recently activated a hifer beacon on 13.55544 MHz. I set the power 
according to guidance at http://lwca.org/sitepage/part15/index.htm, 
which indicates 4.8 mW is allowable for half-wave dipoles and 
quarter-wave verticals over ground planes (I'm using the former). 
However, I just calculated what 10,000 uV/m at 30 m represents and I 
think that guidance is in error. The maximum field strength implies a 
received power of 1.72 uW by a half-wave dipole. For free-space, 
far-field propagation this would be produced by a transmit power of 1.86 
mW (2.7 dBm) using a half-wave dipole. If an isotropic radiator is 
assumed then the answer is 3.05 mW, matching the suggested 4.8 mW. Thus, 
it seems the lwca reference applies to an isotropic radiator, not a 
dipole or vertical. Comments appreciated.

73, Garry, K3SIW, EN52ta, Elgin, IL