47 CFR 18.305 - Field strength limits.
(a) ISM equipment operating on a frequency specified in § 18.301 is permitted unlimited radiated energy in the band specified for that frequency.
(b) The field strength levels of emissions which lie outside the bands specified in § 18.301, unless otherwise indicated, shall not exceed the following:
|Equipment||Operating frequency||RF Power generated by equipment (watts)||Field strength limit (uV/m)||Distance (meters)|
|1 Field strength may not exceed 10 μV/m at 1600 meters. Consumer equipment operating below 1000 MHz is not permitted the increase in field strength otherwise permitted here for power over 500 watts.|
|2 Reduced to the greatest extent possible.|
|3 Field strength may not exceed 10 μV/m at 1600 meters. Consumer equipment is not permitted the increase in field strength otherwise permitted here for over 500 watts.|
|4 Induction cooking ranges manufactured prior to February 1, 1980, shall be subject to the field strength limits for miscellaneous ISM equipment.|
|Any type unless otherwise specified (miscellaneous)||Any ISM frequency||Below 500500 or more||2525×SQRT(power/500)||300 1300|
|Any non-ISM frequency||Below 500500 or more||1515×SQRT(power/500)||300 1300|
|Industrial heaters and RF stabilized arc welders||On or below 5,725 MHzAbove 5,725 MHz||AnyAny||10(2)||1,600(2)|
|Medical diathermy||Any ISM frequencyAny non-ISM frequency||AnyAny||2515||300300|
|Ultrasonic||Below 490 kHz||Below 500500 or more||2,400/F(kHz)2,400/F(kHz)× SQRT(power/500)||300 3300|
|490 to 1,600 kHzAbove 1,600 kHz||AnyAny||24,000/F(kHz)15||3030|
|Induction cooking ranges||Below 90 kHzOn or above 90 kHz||AnyAny||1,500300||430 430|
|Frequency (MHz)||Field strength limit at 30 meters (μV/m)|
1. The tighter limit shall apply at the boundary between two frequency ranges.
2. Testing for compliance with these limits may be made at closer distances, provided a sufficient number of measurements are taken to plot the radiation pattern, to determine the major lobes of radiation, and to determine the expected field strength level at 30, 300, or 1600 meters. Alternatively, if measurements are made at only one closer fixed distance, then the permissible field strength limits shall be adjusted using 1/d as an attenuation factor.
[50 FR 36070, Sept. 5, 1985, as amended at 51 FR 17970, May 16, 1986; 52 FR 43197, Nov. 10, 1987]
Title 47 published on 2013-10-01
no entries appear in the Federal Register after this date.