L band refers to four different bands of the electromagnetic spectrum: 40 to 60 GHz (NATO), 1 to 2 GHz (IEEE), 1565 nm to 1625 nm (optical), and around 3.5 micrometres (infrared astronomy).

  NATO L band

The NATO L band is defined as the frequency band between 40 and 60 GHz (5–7.5 mm).

  IEEE L band

  Military use

In the United States and overseas territories, the L band is held by the military for telemetry, thereby forcing digital radio to in-band on-channel (IBOC) solutions. Digital Audio Broadcasting (DAB) is typically done in the 1452–1492-MHz range as in most of the world, but other countries also use VHF and UHF bands.

  GNSS

The Global Positioning System carriers are in the L band, centered at 1176.45 MHz (L5), 1227.60 MHz (L2), 1381.05 MHz (L3), and 1575.42 MHz (L1) frequencies.

• The Galileo Navigation System uses the L-band similarly to GPS.
• The GLONASS System uses the L-band similarly to GPS.

  Telecommunications use

GSM mobile phones operate at 800–900 and 1800–1900 MHz. Iridium Satellite LLC phones use frequencies between 1616 and 1626.5 MHz^[1] to communicate with the satellites. Inmarsat and LightSquared terminals use frequencies between 1525 and 1646.5 MHz to communicate with the satellites.

  Amateur radio

The Radio Regulations of the International Telecommunication Union allow amateur radio operations in the frequency range 1,240 to 1,300 MHz, and amateur satellite up-links are allowed in the range 1,260 to 1,270 MHz. This is known as the 23-centimeter band by radio amateurs and the L-band by AMSAT.

  Digital Audio Broadcasting (Earth Orbital)

WorldSpace satellite radio broadcasts in the 1467–1492 MHz L sub-band.

  DAB L band usage

The following blocks are used for T-DAB (terrestrial) broadcasts:

The following blocks are used for S-DAB (satellite) broadcasts:

Note: Canada uses slightly different central frequencies for L-band DAB while in many European countries DAB is limited part of Band III due to television and mobile two way radio using the rest.

  Physics issues relating to band use

The band also contains the hyperfine transition of neutral hydrogen (the hydrogen line, 1420 MHz), which is of great astronomical interest as a means of imaging the normally invisible neutral atomic hydrogen in interstellar space. Consequently parts of the L-band are protected radio astronomy allocations worldwide.

  Optical communications L band

L band is also used in optical communications to refer to the wavelength range 1565 nm to 1625 nm.

  Infrared astronomy

  Atmospheric windows in the infrared. The L band is the transmission window centred on 3.5 micrometres

In infrared astronomy, the L band refers to an atmospheric transmission window centred on 3.5 micrometres (in the mid-infrared).

  Other microwave bands

The microwave spectrum is usually defined as electromagnetic energy ranging from approximately 1 GHz to 100 GHz in frequency, but older usage includes lower frequencies. Most common applications are within the 1 to 40 GHz range. Microwave frequency bands, as defined by the Radio Society of Great Britain (RSGB), are shown in the table below:

Footnote: P band is sometimes incorrectly used for Ku Band. "P" for "previous" was a radar band used in the UK ranging from 250 to 500 MHz and now obsolete per IEEE Std 521, see [1] and [2]. For other definitions see Letter Designations of Microwave Bands

  See also

• Earth observation satellites transmission frequencies

  References