Radio Spectrum

Bands

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 thecompatibility 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.[citation needed]
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

Named frequency bands

General

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

Amateur radio frequencies

The range of allowed amateur radio frequencies varies between countries. The article Amateur radio frequency allocations lists frequencies allocated for amateur radio use.

IEEE US

Band	Frequency range	Origin of name[2]
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 Frequencies from 216 to 450 MHz were sometimes called P-band: Previous, since early British radar used this band but later switched to higher frequencies.
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.^[3]

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 ofWireless Engineer in 1942. (For example, the approximate geometric mean of Band 7 is 10 MHz, or 10⁷ Hz.)^[4]

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)