Unlicensed broadcasting
Unlicensed broadcasts on the
FM broadcast band (88 to 108 MHz) are limited to a
field strength of 250
µV/
m at a distance of 3 meters from the
antenna. This is equivalent to 0.01 microwatts.
[1] Emissions must be kept within the 88.0 to 108.0 MHz band under Part 15 rules.
The FM broadcast band is limited but not restricted to 87.9 MHz (but see note below on TV) to 107.9 MHz. There are a few class D FM stations on 87.9 MHz.
[2] Any unlicensed 88 to 108 MHz broadcasting with a signal strength greater than 250 µV/m at a distance of 3 m from the antenna is punishable by law and confiscation of all broadcast equipment.
Unlicensed broadcasts on the
TV broadcast bands are prohibited, except for certain
medical telemetry devices. 87.5 to 88.0
MHz is considered part of the
VHF TV band (channel 6 audio is on 87.75), though it shows up on most FM
tuners. For TV, 15.241 and 15.242 deal with high VHF (channels 7 to 13), 15.242 also deals with UHF.
On the standard AM broadcast band transmission is limited to 100 milliwatts of power (with restrictions on size, height and type of antenna) or, alternatively, under 15.221, if the AM transmission originates on the
campus of an educational institution, the transmission can theoretically be any power so long as it does not exceed the field strength limits stated in 15.209 at the perimeter of the campus, 24000/F(kHz)
µV/
m.