47 C.F.R. § 18.305 Field strength limits.
Title 47 - Telecommunication
(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: (c) The field strength limits for RF lighting devices shall be the following: Notes
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: Telecommunication
PART 18—INDUSTRIAL, SCIENTIFIC, AND MEDICAL EQUIPMENT
Subpart C—Technical Standards
§ 18.305 Field strength limits.
---------------------------------------------------------------------------------------------------------------- RF Power generated by Field strength limit Distance Equipment Operating frequency equipment (watts) (uV/m) (meters)----------------------------------------------------------------------------------------------------------------Any type unless otherwise Any ISM frequency.... Below 500............ 25.................. 300 specified (miscellaneous). 500 or more.......... 25xSQRT(power/500).. \1\300 Any non-ISM frequency Below 500............ 15.................. 300 500 or more.......... 15xSQRT(power/500).. \1\300Industrial heaters and RF On or below 5,725 MHz Any.................. 10.................. 1,600 stabilized arc welders. Above 5,725 MHz...... Any.................. (\2\)............... (\2\)Medical diathermy................. Any ISM frequency.... Any.................. 25.................. 300 Any non-ISM frequency Any.................. 15.................. 300Ultrasonic........................ Below 490 kHz........ Below 500............ 2,400/F(kHz)........ 300 500 or more.......... 2,400/F(kHz)x \3\300 SQRT(power/500). 490 to 1,600 kHz..... Any.................. 24,000/F(kHz)....... 30 Above 1,600 kHz...... Any.................. 15.................. 30Induction cooking ranges.......... Below 90 kHz......... Any.................. 1,500............... \4\30 On or above 90 kHz... Any.................. 300................. \4\30----------------------------------------------------------------------------------------------------------------\1\ Field strength may not exceed 10 mV/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 mV/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.
------------------------------------------------------------------------ Field strength limit at 30 meters Frequency (MHz) (mV/m)------------------------------------------------------------------------Non-consumer equipment: 30-88........................... 30 88-216.......................... 50 216-1000........................ 70Consumer equipment: 30-88........................... 10 88-216.......................... 15 216-1000........................ 20------------------------------------------------------------------------
