FCC Rules for ISM Band Wireless Equipment
In 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, http://www.fcc.gov/
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 Power Output Rules for ISM bands
The limits are three:
The responsibility for staying within these power limits falls on the operator
(or, if professionally installed, on the installer).
- 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
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.