[Antennas] 60 Meters now requires knowing antennas

2003年6月19日 11:11:25 -0500

The following, from ARRL states:
"According to Part 97.303(s), a half-wave dipole on the 5 MHz allocation 
will be presumed to have a gain of 0 dBd. ''Licensees using other antennas 
must maintain in their station records either manufacturer data on the 
antenna gain or calculations of the antenna gain,'' states the newest 
addition to the FCC's Amateur Service rules.
Because the new rules also require hams to run no more than 50 W effective 
radiated power (ERP) on the new channels, the choice of antenna becomes an 
important compliance factor. The FCC rules stipulate, ''For the purpose of 
computing ERP, the transmitter PEP will be multiplied (by) the antenna gain 
relative to a dipole or the equivalent calculation in decibels.'' "
AM I the only one confused by this? Gain relative to a dipole at what 
height? At what take off angle are they considering? Do they mean a half 
wave dipole or any old dipole. IF a long wire, many wavelengths long can be 
considered a dipole, then the gain can be greater than a half wave dipole at 
the same height. But, if my long dipole is sky wave propogation only, it has 
less gain at low angles than a dipole at 1/2 wavelength over ground.
Pat W0OPW
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