Measurements of Electromagnetic Fields at Amateur Radio Stations
OET Report ASD-9601, January 1996
The FCC's Office of Engineering and Technology (OET) has released a technical report entitled, "Measurements of Environmental Electromagnetic Fields at Amateur Radio Stations." The report describes a joint measurement study of environmental radio frequency (RF) fields in the vicinity of nine amateur radio stations that was conducted by the FCC and the U.S. Environmental Protection Agency (EPA) in southern California. This information will be useful to the FCC in determining how to implement newly revised guidelines for human exposure to RF energy. Amateur stations were chosen that represented a variety of antenna and equipment types, many of which are commonly used by amateur radio operators.
Measurements of electric and magnetic field strength were made in areas near amateur antennas and equipment in order to determine typical and "worst case" exposure levels of amateur radio operators, their families and other individuals who live or work in the vicinity of these stations. Measurements were made using instrumentation appropriate for the particular transmitting frequency being used at a given location. Both broadband and narrow band instruments were used.
For most of the stations surveyed, current RF protection guidelines for field strength and power density were not exceeded in accessible areas. The highest readings in accessible areas were generally associated with vehicle-mounted antennas. However, when "duty factors" are taken into account routine exposures from such antennas would be expected to comply with safety guidelines.
If maximum permissible power levels and different facility configurations are used, higher exposure levels than those measured here cannot be ruled out. Such exposures could affect the amateur operator or other individuals in the immediate vicinity of a station. However, it is concluded that appropriate precautionary measures and facility siting should be sufficient to prevent exposures that are in excess of safety guidelines.