Regulations last checked for updates: Jan 18, 2025
Title 47 - Telecommunication last revised: Jan 15, 2025
§ 18.301 - Operating frequencies.
ISM equipment may be operated on any frequency above 9 kHz except as indicated in § 18.303. The following frequency bands, in accordance with § 2.106 of the rules, are designated for use by ISM equipment:
| ISM frequency
| Tolerance
|
|---|
| 6.78 MHz | ± 15.0 kHz
|
| 13.56 MHz | ± 7.0 kHz
|
| 27.12 MHz | ± 163.0 kHz
|
| 40.68 MHz | ± 20.0 kHz
|
| 915 MHz | ± 13.0 MHz
|
| 2450 MHz | ± 50.0 MHz
|
| 5800 MHz | ± 75.0 MHz
|
| 24.125 GHz | ± 125.0 MHz
|
| 61.25 GHz | ± 250.0 MHz
|
| 122.50 GHz | ± 500.0 MHz
|
| 245.00 GHz | ± 1.0 GHz |
§ 18.303 - Prohibited frequency bands.
Operation of ISM equipment within the following safety, search and rescue frequency bands is prohibited: 490-510 kHz, 2170-2194 kHz, 8354-8374 kHz, 121.4-121.6 MHz, 156.7-156.9 MHz, and 242.8-243.2 MHz.
§ 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)
|
|---|
| Any type unless otherwise specified (miscellaneous) | Any ISM frequency | Below 500
500 or more | 25
25 × SQRT(power/500) | 300
1300
|
| | Any non-ISM frequency | Below 500
500 or more | 15
15 × SQRT(power/500) | 300
1300
|
| Industrial heaters and RF stabilized arc welders | On or below 5,725 MHz
Above 5,725 MHz | Any
Any | 10
(
2) | 1,600
(
2)
|
| Medical diathermy | Any ISM frequency
Any non-ISM frequency | Any
Any | 25
15 | 300
300
|
| Ultrasonic | Below 490 kHz | Below 500
500 or more | 2,400/F(kHz)
2,400/F(kHz) × SQRT(power/500) | 300
3300
|
| | 490 to 1,600 kHz
Above 1,600 kHz | Any
Any | 24,000/F(kHz)
15 | 30
30
|
| Induction cooking ranges | Below 90 kHz
On or above 90 kHz | Any
Any | 1,500
300 |
430
430
|
(c) The field strength limits for RF lighting devices shall be the following:
| Frequency (MHz)
| Field strength limit at 30 meters (μV/m)
|
|---|
| Non-consumer equipment:
| |
| 30-88 | 30
|
| 88-216 | 50
|
| 216-1000 | 70
|
| Consumer equipment:
| |
| 30-88 | 10
|
| 88-216 | 15
|
| 216-1000 | 20 |
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]
§ 18.307 - Conduction limits.
For the following equipment, when designed to be connected to the public utility (AC) power line the radio frequency voltage that is conducted back onto the AC power line on any frequency or frequencies shall not exceed the limits in the following tables. Compliance with the provisions of this paragraph shall be based on the measurement of the radio frequency voltage between each power line and ground at the power terminal using a 50 μH/50 ohms line impedance stabilization network (LISN).
(a) All Induction cooking ranges and ultrasonic equipment:
| Frequency of emission (MHz)
| Conducted limit (dBμV)
|
|---|
| Quasi-peak
| Average
|
|---|
| 0.009-0.05 | 110 | —
|
| 0.05-0.15 | 90-80 * | —
|
| 0.15-0.5 | 66 to 56 * | 56 to 46 *
|
| 0.5-5 | 56 | 46
|
| 5-30 | 60 | 50
|
(b) All other part 18 consumer devices:
| Frequency of emission (MHz)
| Conducted limit (dBμV)
|
|---|
| Quasi-peak
| Average
|
|---|
| 0.15-0.5 | 66 to 56 * | 56 to 46 *
|
| 0.5-5 | 56 | 46
|
| 5-30 | 60 | 50
|
(c) RF lighting devices:
| Frequency (MHz)
| Maximum RF line voltage measured with a 50 uH/50 ohm LISN (uV)
|
|---|
| Non-consumer equipment:
| |
| 0.45 to 1.6 | 1,000
|
| 1.6 to 30 | 3,000
|
| Consumer equipment:
| |
| 0.45 to 2.51 | 250
|
| 2.51 to 3.0 | 3,000
|
| 3.0 to 30 | 250 |
(d) If testing with a quasi-peak detector demonstrates that the equipment complies with the average limits specified in the appropriate table in this section, additional testing to demonstrate compliance using an average detector is not required.
(e) These conduction limits shall apply only outside of the frequency bands specified in § 18.301.
(f) For ultrasonic equipment, compliance with the conducted limits shall preclude the need to show compliance with the field strength limits below 30 MHz unless requested by the Commission.
(g) The tighter limits shall apply at the boundary between two frequency ranges.
[50 FR 36067, Sept. 5, 1985, as amended at 52 FR 43198, Nov. 10, 1987; 64 FR 37419, July 12, 1999; 67 FR 45671, July 10, 2002]
§ 18.309 - Frequency range of measurements.
(a) For field strength measurements:
| Frequency band in which device operates (MHz)
| Range of frequency measurements
|
|---|
| Lowest frequency
| Highest frequency
|
|---|
| Below 1.705 | Lowest frequency generated in the device, but not lower than 9 kHz | 30 MHz.
|
| 1.705 to 30 | Lowest frequency generated in the device, but not lower than 9 kHz | 400 MHz.
|
| 30 to 500 | Lowest frequency generated in the device or 25 MHz, whichever is lower | Tenth harmonic or 1,000 MHz, whichever is higher.
|
| 500 to 1,000 | Lowest frequency generated in the device or 100 MHz, whichever is lower | Tenth harmonic.
|
| Above 1,000 | ......do | Tenth harmonic or highest detectable emission. |
(b) For conducted powerline measurements, the frequency range over which the limits are specified will be scanned.
[50 FR 36070, Sept. 5, 1985, as amended at 51 FR 17971, May 16, 1986]
§ 18.311 - Methods of measurement.
The measurement techniques used to determine compliance with the technical requirements of this part are set out in FCC MP-5, “FCC Methods of Measurements of Radio Noise Emissions from Industrial, Scientific, and Medical equipment,” or compliance measurements made in accordance with the specific procedures otherwise authorized by the Commission.
[82 FR 50835, Nov. 2, 2017]
§ 18.313 - Radio frequency exposure requirements.
Radio frequency devices operating under the provisions of this part are subject to the radio frequency radiation exposure requirements specified in §§ 1.1307(b), 1.1310, 2.1091, and 2.1093 of this chapter, as appropriate.
[85 FR 18150, Apr. 1, 2020]
source: 50 FR 36067, Sept. 5, 1985, unless otherwise noted.
cite as: 47 CFR 18.301