Section 2.101 - Frequency and wavelength bands(a) The radio spectrum shall be subdivided into nine frequency bands, which shall be designated by progressive whole numbers in accordance with the following table. As the unit of frequency is the hertz (Hz), frequencies shall be expressed: (1) In kilohertz (kHz), up to and including 3 000 kHz;(2) In megahertz (MHz), above 3 MHz, up to and including 3 000 MHz;(3) In gigahertz (GHz), above 3 GHz, up to and including 3 000 GHz.(b) However, where adherence to these provisions would introduce serious difficulties, for example in connection with the notification and registration of frequencies, the lists of frequencies and related matters, reasonable departures may be made.Table 1 to Paragraph (b)
| Band No. | Symbols | Frequency range (lower limit exclusive, upper limit inclusive) | Corresponding metric subdivision |
| 4 | VLF | 3 to 30 kHz | Myriametric waves. |
| 5 | LF | 30 to 300 kHz | Kilometric waves. |
| 6 | MF | 300 to 3 000 kHz | Hectometric waves. |
| 7 | HF | 3 to 30 MHz | Decametric waves. |
| 8 | VHF | 30 to 300 MHz | Metric waves. |
| 9 | UHF | 300 to 3 000 MHz | Decimetric waves. |
| 10 | SHF | 3 to 30 GHz | Centimetric waves. |
| 11 | EHF | 30 to 300 GHz | Millimetric waves. |
| 12 | | 300 to 3 000 GHz | Decimillimetric waves. |
Note 1: "Band N" (N = band number) extends from 0.3 * 10N Hz to 3 * 10N Hz.
Note 2: Prefix: k = kilo (103), M = mega (106), G = giga (109).
(c) In communications between administrations and the ITU, no names, symbols or abbreviations should be used for the various frequency bands other than those specified in this section. kHz: For frequencies up to 28 000 kHz inclusive;
MHz: For frequencies above 28 000 kHz up to 10 500 MHz inclusive; and
GHz: For frequencies above 10 500 MHz.
70 FR 46583, Aug. 10, 2005; 70 FR 53074, Sept. 7, 2005; 75 FR 62933, Oct. 13, 2010; 80 FR 38823, July 7, 2015; 85 FR 38632, June 26, 2020