§  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.1

   1In the application of the ITU Radio Regulations, the
   Radiocommunication Bureau uses the following units:

   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.

   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 × 10^N Hz to 3 ×
   10^N Hz.

   Note 2: Prefix: k = kilo (10^3), M = mega (10^6), G = giga (10^9).

   (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.

   [ 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]