FCC Rules for ISM Band Wireless EquipmentIn the
USA, management of the electromagnetic spectrum is the
responsibility of the Federal Communcations Commission
(FCC). The FCC regulates not only the "intentional
radiation" of radio transmitters, but also the
"unintentional radiation" of noise from all sorts of
electrical equipment. The FCC regulations appear in title
47 of the United States Code of Federal Regulations
(47CFR), and radio spectrum issues are the subject of
part 15 of the FCC rules, or 47CFR15 in brief.
The FCC website , has a lot
of material online, including FCC rules
(47CFR).
FCC Rules Applicable to ISM-SS
Radios(94 page
PDF file of FCC rules part 15)
| FCC 15.107 |
Conducted Emissions including AC Line |
| FCC 15.109 |
Unintentional radiation from ITE |
| FCC 15.205 |
Restricted bands of operation |
| FCC 15.207 |
Conducted emissions from intentional
radiators |
| FCC 15.209 |
Radiated emission limits, general
requirements |
| FCC 15.247 |
ISM Band Communication Equipment |
Summary of FCC Power Output Rules for ISM
bandsThe limits are three:
- Maximum transmitter output is 1W (30 dBm)
(47CFR15.247.b.1)
- Maximum EIRP is 4W (36 dBm) (47CFR15.247.b.3) i.e.
for every dB of antenna gain above 6dBi, transmitter
output must be reduced by 1dBm; per this rule, a 24dBi
antenna limits the output power to 12 dBm which is
16mW
- For fixed point to point operation in ISM2.4, peak
output need only be reduced by 1 dBm for every 3 dBi of
antenna gain above 6 (47CFR15.247.b.3.i) i.e. per this
rule, a 24 dBi antenna may be fed by 24 dBm or 250
mW
- In ISM5.8, you can apply all the antenna gain you
want (47CFR15.247.b.3.ii) with no reduction in output
power.
The responsibility for staying within these power
limits falls on the operator (or, if professionally
installed, on the installer).
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