Radio spectrum

Radio spectrum refers to the part of the electromagnetic spectrum corresponding to radio frequencies – that is, frequencies lower than around 300 GHz (or, equivalently, wavelengths longer than about 1 mm).

Different parts of the radio spectrum are used for different radio transmission technologies and applications. Radio spectrum is typically government regulated in developed countries, and in some cases is sold or licensed to operators of private radio transmission systems (for example, cellular telephone operators or broadcast television stations). Ranges of allocated frequencies are often referred to by their provisioned use (for example, cellular spectrum or television spectrum).

By frequency

A band is a small section of the spectrum of radio communication frequencies, in which channels are usually used or set aside for the same purpose.

Above 300 GHz, the absorption of electromagnetic radiation by Earth's atmosphere is so great that the atmosphere is effectively opaque, until it becomes transparent again in the infrared and optical window frequency ranges.

To prevent interference and allow for efficient use of the radio spectrum, similar services are allocated in bands. For example, broadcasting, mobile radio, or navigation devices, will be allocated in non-overlapping ranges of frequencies.

Each of these bands has a basic bandplan which dictates how it is to be used and shared, to avoid interference and to set protocol for the compatibility of transmitters and receivers.

As a matter of convention, bands are divided at wavelengths of 10ⁿ metres, or frequencies of 3×10ⁿ hertz. For example, 30 MHz or 10 m divides shortwave (lower and longer) from VHF (shorter and higher). These are the parts of the radio spectrum, and not its frequency allocation.

Band name	Abbr	ITU band	Frequency and wavelength in air	Example uses
sub-hertz	subHz	0	< 3 Hz > 100,000 km	Natural and man-made electromagnetic waves (millihertz, microhertz, nanohertz) from earth, ionosphere, sun, planets, etc.
Extremely low frequency	ELF	1	3–30 Hz 100,000 km – 10,000 km	Communication with submarines
Super low frequency	SLF	2	30–300 Hz 10,000 km – 1000 km	Communication with submarines, Main power (50/60Hz)
Ultra low frequency	ULF	3	300–3000 Hz 1000 km – 100 km	Communication within mines
Very low frequency	VLF	4	3–30 kHz 100 km – 10 km	Submarine communication, avalanche beacons, wireless heart rate monitors, geophysics
Low frequency	LF	5	30–300 kHz 10 km – 1 km	Navigation, time signals, AM longwave broadcasting, RFID
Medium frequency	MF	6	300–3000 kHz 1 km – 100 m	AM (medium-wave) broadcasts, amateur radio
High frequency	HF	7	3–30 MHz 100 m – 10 m	Shortwave broadcasts, citizens' band radio, amateur radio and over-the-horizon aviation communications, RFID, Over-the-horizon radar, Automatic link establishment (ALE) / Near Vertical Incidence Skywave (NVIS) radio communications, Marine and mobile radio telephony
Very high frequency	VHF	8	30–300 MHz 10 m – 1 m	FM, television broadcasts and line-of-sight ground-to-aircraft and aircraft-to-aircraft communications. Land Mobile and Maritime Mobile communications, amateur radio
Ultra high frequency	UHF	9	300–3000 MHz 1 m – 100 mm	Television broadcasts, microwave ovens, mobile phones, wireless LAN, Bluetooth, ZigBee, GPS and two-way radios such as Land Mobile, FRS and GMRS radios, amateur radio
Super high frequency	SHF	10	3–30 GHz 100 mm – 10 mm	Microwave devices, wireless LAN, most modern radars, communications satellites, amateur radio
Extremely high frequency	EHF	11	30–300 GHz 10 mm – 1 mm	Radio astronomy, high-frequency microwave radio relay, microwave remote sensing, amateur radio
Terahertz	THz	12	300–3,000 GHz 1 mm – 100 𝜇m	Terahertz imaging – a potential replacement for X-rays in some medical applications, ultrafast molecular dynamics, condensed-matter physics, terahertz time-domain spectroscopy, terahertz computing/communications, sub-mm remote sensing

IEEE US

Band	Frequency range	Origin of name
HF band	3 to 30 MHz	High Frequency
VHF band	30 to 300 MHz	Very High Frequency
UHF band	300 to 1000 MHz	Ultra High Frequency
L band	1 to 2 GHz	Long wave
S band	2 to 4 GHz	Short wave
C band	4 to 8 GHz	Compromise between S and X
X band	8 to 12 GHz	Used in WW II for fire control, X for cross (as in crosshair)
Ku band	12 to 18 GHz	Kurz-under
K band	18 to 27 GHz	German Kurz (short)
Ka band	27 to 40 GHz	Kurz-above
V band	40 to 75 GHz
W band	75 to 110 GHz	W follows V in the alphabet
mm band	110 to 300 GHz

ITU

The ITU radio bands are designations defined in the ITU Radio Regulations. Provision No. 2.1 states that "the radio spectrum shall be subdivided into nine frequency bands, which shall be designated by progressive whole numbers in accordance with the following table.

The table originated with a recommendation of the IVth CCIR meeting, held in Bucharest in 1937, and was approved by the International Radio Conference held at Atlantic City in 1947. The idea to give each band a number, in which the number is the logarithm of the approximate geometric mean of the upper and lower band limits in Hz, originated with B.C. Fleming-Williams, who suggested it in a letter to the editor of Wireless Engineer in 1942. (For example, the approximate geometric mean of Band 7 is 10 MHz, or 10⁷ Hz.)

Table of ITU Radio Bands

Band Number	Symbols	Frequency Range	Wavelength Range	Typical sources
1	ELF	3 to 30 Hz	10,000 to 100,000 km	deeply-submerged submarine communication
2	SLF	30 to 300 Hz	1000 to 10,000 km	submarine communication, ac power grids
3	ULF	300 to 3 kHz	100 to 1000 km	earth quakes, earth mode communication
4	VLF	3 to 30 kHz	10 to 100 km	near-surface submarine communication,
5	LF	30 to 300 kHz	1 to 10 km	AM broadcasting, aircraft beacons
6	MF	300 to 3000 kHz	100 to 1000 m	AM broadcasting, aircraft beacons
7	HF	3 to 30 MHz	10 to 100 m	Skywave long range radio communication: shortwave broadcasting, military, maritime, diplomatic, amateur two-way radio
8	VHF	30 to 300 MHz	1 to 10 m	FM radio broadcast, television broadcast, PMR, DVB-T, MRI
9	UHF	300 to 3000 MHz	10 to 100 cm	PMR, television broadcast, microwave oven, GPS, mobile phone communication (GSM, UMTS, 3G, HSDPA), cordless phones (DECT), WLAN (Wi-Fi 802.11 b/g), Bluetooth
10	SHF	3 to 30 GHz	1 to 10 cm	DBS satellite television broadcasting, WLAN (Wi-Fi 802.11 a), microwave relays, WiMAX, radars
11	EHF	30 to 300 GHz	1 to 10 mm	microwave relays, intersatellite links, WiMAX, high resolution radar, directed-energy weapon (Active Denial System), Security screening (Millimeter wave scanner)

EU, NATO, US ECM frequency designations

Band	Frequency range
A band	0 to 0.25 GHz
B band	0.25 to 0.5 GHz
C band	0.5 to 1.0 GHz
D band	1 to 2 GHz
E band	2 to 3 GHz
F band	3 to 4 GHz
G band	4 to 6 GHz
H band	6 to 8 GHz
I band	8 to 10 GHz
J band	10 to 20 GHz
K band	20 to 40 GHz
L band	40 to 60 GHz
M band	60 to 100 GHz

Waveguide frequency bands

Band	Frequency range
R band	1.70 to 2.60 GHz
D band	2.20 to 3.30 GHz
S band	2.60 to 3.95 GHz
E band	3.30 to 4.90 GHz
G band	3.95 to 5.85 GHz
F band	4.90 to 7.05 GHz
C band	5.85 to 8.20 GHz
H band	7.05 to 10.10 GHz
X band	8.2 to 12.4 GHz
Ku band	12.4 to 18.0 GHz
K band	15.0 to 26.5 GHz
Ka band	26.5 to 40.0 GHz
Q band	33 to 50 GHz
U band	40 to 60 GHz
V band	50 to 75 GHz
W band	75 to 110 GHz
Y band	325 to 500 GHz

By application

Broadcasting

Broadcast frequencies:

• Longwave AM Radio = 148.5 – 283.5 kHz (LF)
• Mediumwave AM Radio = 530 kHz – 1710 kHz (MF)
• Shortwave AM Radio = 3 MHz – 30 MHz (HF)

Designations for television and FM radio broadcast frequencies vary between countries, see Television channel frequencies and FM broadcast band. Since VHF and UHF frequenies are desirable for many uses in urban areas, in North America some parts of the former television broadcasting band have been reassigned to cellular phone and various land mobile communcations systems. Even within the allocation still dedicated to television, TV-band devices use channels without local broadcasters.

The Apex band in the United States was a pre-WWII allocation for VHF audio broadcasting; it was made obsolete after the introduction of FM broadcasting.

Air band

Airband refers to VHF frequencies used for navigation and voice communication with aircraft. Trans-oceanic aircraft also carry HF radio and satellite transcievers.

Marine band

The greatest incentive for development of radio was the need to communicate with ships out of visual range of shore. From the very early days of radio, large oceangoing vessels carried powerful longwave and medium-wave transmitters. High-frequency allocations are still designated for ships, although satellite systems have taken over some of the safety applications previously served by 500 kHz and other frequencies. 2182 kHz is a medium-wave frequency still used for marine emergency communication.

Marine VHF radio is used in coastal waters and relatively short-range communication between vessels and to shore stations. Radios are channelized, with different channels used for different purposes; marine Channel 16 is used for calling and emergencies.

Amateur radio frequencies

Amateur radio frequency allocations vary around the world. Several bands are common for amateurs world-wide, usually in the shortwave part of the spectrum. Other bands are national or regional allocations only due to differing allcations for other services, especially in the VHF and UHF parts of the radio spectrum.

Citizens' band

Citizens' band radio is allocated in many countries, using channelized radios in the upper HF part of the spectrum (around 27 MHz). It used for personal, small business and hobby purposes. Other frequency allocations are used for similar services in differnt jurisdictions, for example UHF CB is allocated in Australia.

Industrial, scientific, medical

The ISM bands were initially reserved for non-communications uses of RF energy, such as microwave ovens, radio-frequency heating, and similar purposes. Many unlicensed devices such as cordless telephones or wireless computer networks now use ISM frequencies, with no expectation of regulatory protection from primary ISM devices.

Land mobile bands

Bands of frequecies, especially in the VHF and UHF parts of the spectrum, are allocated for communication between fixed base stations and vehicle-mounted or portable transcievers. In the United States these servciess are informally known as business band radio.

Radar

Radar applications use relatively high power pulse transmitters and sensitive receivers, so radar is operated on bands not used for other purposes. Most radar bands are in the microwave part of the spectrum, although certain important applications for meterology make use of powerful transmitters in the UHF band.

See also

• Bandplan
• DXing
• Frequency allocation
• Two-way radio

References

• ITU-R Recommendation V.431: Nomenclature of the frequency and wavelength bands used in telecommunications. International Telecommunication Union, Geneva.
• IEEE Standard 521-2002: Standard Letter Designations for Radar-Frequency Bands
• AFR 55-44/AR 105-86/OPNAVINST 3430.9A/MCO 3430.1, 27 October 1964 superseded by AFR 55-44/AR 105-86/OPNAVINST 3430.1A/MCO 3430.1A, 6 December 1978: Performing Electronic Countermeasures in the United States and Canada, Attachment 1,ECM Frequency Authorizations.

External links

• UnwantedEmissions.com A reference to radio spectrum allocations.
• "Radio spectrum: a vital resource in a wireless world" European Commission policy.