Post by Admin on Aug 19, 2014 22:08:03 GMT
For those of us in the U.S., we have to follow the FCC Part 15 rules. Questions about permissible power levels and antennas for use on the FM band come up.
The FM Part 15 operation is restricted by FIELD STRENGTH. Granted the amount of power and type of antenna have a direct effect on the field strength but the rule does not specify any limits on power or antenna.
The point is, you can use any combination of transmitter and antenna you'd like BUT you must not exceed the limits set by Part 15.239 which is 250 microvolts per meter measured at 3 meters from the antenna.
Most people don't have the equipment to measure this small amount of signal. That being the case, a good rule of thumb is your signal should only cover about 200 to 300 feet. The only way to be certain you are compliant is to have the proper equipment to measure your signal field strength.
The FM Part 15 operation is restricted by FIELD STRENGTH. Granted the amount of power and type of antenna have a direct effect on the field strength but the rule does not specify any limits on power or antenna.
The point is, you can use any combination of transmitter and antenna you'd like BUT you must not exceed the limits set by Part 15.239 which is 250 microvolts per meter measured at 3 meters from the antenna.
Most people don't have the equipment to measure this small amount of signal. That being the case, a good rule of thumb is your signal should only cover about 200 to 300 feet. The only way to be certain you are compliant is to have the proper equipment to measure your signal field strength.