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Amateur radio frequency allocation is done by national telecommunication authorities. Globally, the International Telecommunication Union (ITU) oversees how much radio spectrum is set aside for amateur radio transmissions. Individual amateur stations are free to use any frequency within authorized frequency ranges; authorized bands may vary by the class of the station license.

Radio amateurs use a variety of transmission modes, including Morse code, radioteletype, data, and voice. Specific frequency allocations vary from country to country and between ITU regions as specified in the current ITU HF frequency allocations for amateur radio.^[1] The list of frequency ranges is called a band allocation, which may be set by international agreements, and national regulations. The modes and types of allocations within each frequency band is called a bandplan; it may be determined by regulation, but most typically is set by agreements between amateur radio operators.

National authorities regulate amateur usage of radio bands. Some bands may not be available or may have restrictions on usage in certain countries or regions. International agreements assign amateur radio bands which differ by region.^[2][3]

Band characteristics

Low frequency

• 2200 metres – 135.7–137.8 kHz

Just below the Asian and European longwave broadcast band and far below the commercial AM broadcast band.

Medium frequency

• 630 metres – 472–479 kHz

Just below the commercial AM broadcast band and the maritime radio band.

• 160 metres – 1 800–2 000 kHz (1.800–2.000 MHz)

Just above the commercial AM broadcast band. Allocations in this band vary widely from country to country; it was formerly shared with the largely defunct Loran-A radionavigation system.

This band is often taken up as a technical challenge, since long distance (DX) propagation tends to be more difficult due to higher D layer ionospheric absorption. Long-distance propagation tends to occur only at night, and the band can be notoriously noisy particularly in the summer months.

160 metres is also known as the "top band". For many years it was the longest-wavelength amateur band; although often included among the shortwaves, it is located near the top end of the medium frequency band.

High frequency

Most of the customary band names given below are only nominal wavelengths, not actual wavelengths. For example:

• In the western hemisphere the nominal 80 m band actually ranges between about 85.7–74.9 m, and the international portion from 85.7–83.3 m.
• The nominal "17 m" band actually covers 16.6–16.5 m.
• The nominal "15 m" band actually ranges from 14.28–13.98 m. By common sense, "15 m" band ought to be called "14 m", but that name has been in longtime use for a shortwave broadcast band.

• 80 metres or 80 / 75 meters – 3 500–4 000 kHz – 85.65–74.95 m actual

Best at night, with significant daytime signal absorption. Works best in winter, due to atmospheric noise from hemispheric thunder storms during summer. Only countries in the Americas and few others have access to all of this band; in other parts of the world amateurs are limited to the bottom 300 kHz (or less) (85.65–83.28 m).

In the US and Canada the portion of the band from 3.600–4.000 MHz, regulation permits use of single-sideband voice as well as AM voice; this sub-band is often referred to as "the 75 metre band", in part to distinguish it from the internationally available frequencies below it.

• 60 metres – 5 MHz region – around 56 m

A relatively new allocation and originally only available in a small number of countries such as the United States, United Kingdom, Ireland, Norway, Denmark, and Iceland, but now continuing to expand. In most (but not all) countries, the allocation is broken into channels and may require a special licensing request.

Five 2.8 kHz-wide channels are available in the U.S., centered on 5.332, 5.348, 5.368, 5.373, and 5.405 MHz. Since most radios in SSB mode display the (suppressed) carrier frequency, in USB mode the dial frequencies would all need to be set 1.5 kHz lower. Voice operation is generally in upper sideband mode, which is mandatory in the U.S. . The U.S. and Canada allow 100 Watts in the currently available channels.

The 2015 ITU World Radiocommunication Conference (WRC-15) approved a new worldwide frequency allocation of 5.351.5–5.366.5 MHz to the amateurs on a secondary basis. The allocation limits amateur stations to 15 watts effective isotropic radiated power (EIRP); however some locations will be permit up to 25 W EIRP.

• 40 metres – 7.000–7.300 MHz – 42.83–41.51 m actual

Considered the most reliable all-season long distance (DX) band. Popular for DX at night, 40 metres is also reliable for medium distance (1,500 km / 1,000 miles) contacts during the day. Much of this band was shared with broadcasters, and in most countries the bottom 100 kHz or 200 kHz are available to amateurs. However, due to the high cost of running high-power commercial broadcasting facilities, decreased listenership, and increasing competition from Internet-based international broadcast services, many shortwave broadcasting services are being shut down, leaving the 40 metre band free of other users for amateur radio use.

• 30 metres – 10.100–10.150 MHz – 29.68–29.54 m actual

A very narrow band, which is shared with non-amateur services. It is recommended that only Morse code and data transmissions be used here, and in some countries amateur voice transmission is actually prohibited.

For example, in the US, data, RTTY, and CW are the only modes allowed at a maximum 200 W peak envelope power (PEP) output. Not released for amateur use in a small number of countries.

Due to its location in the centre of the shortwave spectrum, this band provides significant opportunities for long-distance communication at all points of the solar cycle. 30 metres is a WARC band. "WARC" bands are so called due to the 1979 special World Administrative Radio Conference allocation of these newer bands to amateur radio use. Amateur radio contests are not run on the WARC bands.

• 20 metres – 14.000–14.350 MHz – 21.41–20.89 m actual

Considered the most popular DX band; usually most popular during daytime. QRP operators recognize 14.060 MHz as their primary calling frequency within the band. Users of the PSK31 data mode tend to congregate around 14.070 MHz. Analog SSTV activity centers on 14.230 MHz.

• 17 metres – 18.068–18.168 MHz – 16.6–16.5 m actual

Similar to 20 metres, but more sensitive to solar propagation minima and maxima. 17 metres is a WARC band.

• 15 metres – 21.000–21.450 MHz – 14.28–13.98 m actual

Most useful during solar maximum, and generally a daytime band. Daytime sporadic E propagation (1,500 km / 1,000 miles) occasionally occurs on this band.

• 12 metres – 24.890–24.990 MHz – 12.04–12.00 m actual

Mostly useful during daytime, but opens up for DX activity at night, during solar maximum. 12 metres is one of the WARC bands. Propagates via sporadic E and by F2 propagation.

• 10 metres – 28.000–29.700 MHz – 10.71–10.08 m actual

Best long distance (e.g., across oceans) activity is during solar maximum; during periods of moderate solar activity the best activity is found at low latitudes. The band offers useful short to medium range groundwave propagation, day or night.

Due to Sporadic E propagation during the late spring and most of the summer, regardless of sunspot numbers, afternoon short band openings into small geographic areas of up to 1,500 km (1,000 miles) occur. Sporadic E is caused by areas of intense ionization in the E layer of the ionosphere. The causes of sporadic E are not fully understood, but these "clouds" of ionization can provide short-term propagation from 17 metres all the way up to occasional 2 metre openings. FM operations are normally found at the high end of the band (Also repeaters are in the 29.500–29.700 MHz segment in many countries).

Very-high frequencies and ultra-high frequencies

Frequencies above 30 MHz are referred to as Very High Frequency (VHF) region and those above 300 MHz are called Ultra High Frequency (UHF). The allocated bands for amateurs are many megahertz wide, allowing for high-fidelity audio transmission modes (FM) and very fast data transmission modes that are unfeasible for the kilohertz-wide allocations in the HF bands.

VHF
8 metres	40–45 MHz	in parts of ITU Region 1
6 metres	50–54 MHz
	50–52 MHz	In parts of ITU Region 1
4 metres	70–70.5 MHz	in parts of ITU Region 1
2 metres	144–148 MHz
	144–146 MHz	ITU Region 1
1.25 metres	219–220 MHz	Fixed digital message forwarding systems
	222–225 MHz	US & Canada
UHF
70 centimetres	420–450 MHz
	430–440 MHz	in ITU Region 1
33 centimetres	902–928 MHz	in ITU Region 2
23 centimetres	1 240–1 300 MHz
	1 240–1 325 MHz	in UK
13 centimetres	2 300–2 310 MHz	lower segment
	2 390–2 450 MHz	upper segment

While "line of sight" propagation is a primary factor for range calculation, much of the interest in the bands above HF comes from use of other propagation modes. A signal transmitted on VHF from a hand-held portable will typically travel about 5–10 km (3–6 miles) depending on terrain. With a low power home station and a simple antenna, range would be around 50 km (30 miles).

With a large antenna system like a long yagi, and higher power (typically 100 watts or more) contacts of around 1 000 km (600 miles) using the Morse code (CW) and single-sideband (SSB) modes are common. Ham operators seek to exploit the limits of the frequencies usual characteristics looking to learn, understand, and experiment with the possibilities of these enhanced propagation modes.

Sporadic band openings

Occasionally, several different ionospheric conditions allow signals to travel beyond the ordinary line-of-sight limits. Some amateurs on VHF seek to take advantage of "band openings" where natural occurrences in the atmosphere and ionosphere extend radio transmission distances well over their normal range. Many hams listen for hours hoping to take advantage of these occasional extended propagation "openings".

The ionospheric conditions are called sporadic E and anomalous enhancement. Less frequently used anomalous modes are tropospheric scatter and Aurora Borealis (Northern Lights). Moon bounce and satellite relay are also possible.

Sporadic E

Some openings are caused by islands of intense ionization of the upper atmosphere, known as the E Layer ionosphere. These islands of intense ionization are called "sporadic E" and result in erratic but often strong propagation characteristics on the "low band" VHF radio frequencies.

The 6 metre amateur band falls into this category, often called "the magic band", will often "open up" from one small area into another small geographic area 1 000–1 700 km (600–1 000 miles) away during the spring and early summer months. This phenomenon occurs during the fall months, although not as often.

Tropospheric refraction

Band openings are sometimes caused by a weather phenomenon known as a tropospheric "inversion", where a stagnant high pressure area causes alternating stratified layers of warm and cold air generally trapping the colder air beneath. This may make for smoggy or foggy days, but it also causes VHF and UHF radio transmissions to travel or duct along the boundaries of these warm/cold atmospheric layers. Radio signals have been known to travel hundreds, even thousands of kilometres (miles) due to these unique weather conditions.

For example: The longest distance reported contact due to tropospheric refraction on 2 metres is 4 754 km (2 954 miles) between Hawaii and a ship south of Mexico. There were reports of the reception of one way signals from Réunion to Western Australia, a distance of more than 6 000 km (4 000 miles).^[4]

Tropo-scatter happens when water droplets and dust particles refract a VHF or UHF signal over the horizon. Using relatively high power and a high gain antenna, this propagation will give marginal enhanced over-the-horizon VHF and UHF communications up to several hundred kilometres (miles). During the 1970s commercial "scatter site" operators using huge parabolic antennas and high power used this mode successfully for telephone communications services into northern remote Alaska and Canadian communities.

Satellite, buried fibre optic, and terrestrial microwave access have relegated commercial use of tropo-scatter to the history books. Because of high cost and complexity this mode is usually out of reach for the average amateur radio operator.

Anomalous trans-equatorial enhancement

F2 and TE band openings from other ionospheric reflection/refraction modes, or sky-wave propagation as it is known can also occasionally occur on the low band VHF frequencies of 6 or 4 metres, and very rarely on 2 metres (high band VHF) during extreme peaks in the 11 year sunspot cycle.

The longest terrestrial contact ever reported on 2 metres (146 MHz) was between a station in Italy and a station in South Africa, a distance of 7 784 km (4 837 miles), using trans-equatorial anomalous enhancement (TE) of the ionosphere over the geomagnetic equator. This enhancement is known as TE, or trans-equatorial propagation and (usually) occurs at latitudes 2 500–3 000 km (1500–1900 miles) within either side of the equator.^[5]

Auroral backscatter

An intense solar storm causing aurora borealis (northern lights) will also provide occasional propagation enhancement to HF-low (6-metre) band radio waves. Aurorae only occasionally affect signals on the 2 metre band. Signals are often distorted and on the lower frequencies give a curious "watery sound" to normally propagated HF signals. Peak signals usually come from the north, even if the signal originates from a station to the east or west of the receiver. This effect is most significant in the latitudes north of 45 degrees.

Moon bounce (Earth-Moon-Earth)

Amateurs do successfully communicate by bouncing their signals off the surface of the Moon, called Earth-Moon-Earth (EME) transmission.

The mode requires moderately high power (more than 500 watts) and a fairly large, high-gain antenna because round-trip path loss is on the order of 270 dB for 70 cm signals. Return signals are weak and distorted because of the relative velocities of the transmitting station, Moon and the receiving station. The Moon's surface is also very rocky and irregular.

Because of the weak, distorted return signals, Moon bounce communications use digital modes. For example, old-fashioned Morse code or modern JT65, designed for working with weak signals.

Satellite relay

Satellite relay is not really a propagation mode, but rather an active repeater system. Satellites have been highly successful in providing VHF/UHF/SHF users "propagation" beyond the horizon.

Amateurs have sponsored the launch of dozens of communications satellites since the 1970s. These satellites are usually known as OSCARs (Orbiting Satellite Carrying Amateur Radio). Also, the ISS has amateur radio repeaters and radio location services on board.

Amateur television

Amateur television (ATV) is the hobby of transmitting broadcast-compatible video and audio by amateur radio. It also includes the study and building of such transmitters and receivers and the propagation between these two.

In NTSC countries, ATV operation requires the ability to use a 6 MHz wide channel. All bands at VHF or lower are less than 6 MHz wide, so ATV operation is confined to UHF and up. Bandwidth requirements will vary from this for PAL and SECAM transmissions.

ATV operation in the 70 cm band is particularly popular, because the signals can be received on any cable-ready television. Operation in the 33 cm and 23 cm bands is easily augmented by the availability of various varieties of consumer-grade wireless video devices that exist and operate in unlicensed frequencies coincident to these bands.

Repeater ATV operation requires specially-equipped repeaters.

Below the MW broadcast band

Historically, amateur stations have rarely been allowed to operate on frequencies lower than the medium-wave broadcast band, but in recent times, as the historic users of these low frequencies have been vacating the spectrum, limited space has opened up to allow for new amateur radio allocations and special experimental operations.

Since parts of the 500 kHz band are no longer used for regular maritime communications,^{[citation needed]} some countries permit amateur radio radiotelegraph operations in that band. Many countries, however, continue to restrict these frequencies which were historically reserved for maritime and aviation distress calls.^[6]

The 2 200 metre band is available for use in several countries, and the 2007 World Radiocommunication Conference (WRC-07) recommended it as a worldwide amateur allocation. Before the introduction of the 2 200 metre band in the U.K. in 1998, operation on the even lower frequency of 73 kHz, in the LF time signal band, was allowed from 1996–2003.

ITU Region 1

ITU Region 1 corresponds to Europe, Russia, Africa and the Middle East. For ITU region 1, Radio Society of Great Britain's band plan will be more definitive (click on the buttons at the bottom of the page).

• Low Frequency (LF) (30 to 300 kHz)
  • 2200 metres (135.7 to 137.8 kHz)
• Medium Frequency (MF) (300 to 3 MHz)
  • 630 metres (472 to 479 kHz)
• High Frequency (HF) (3 to 30 MHz)
  • see Table of amateur MF and HF bandplans
• Very High Frequency (VHF) (30 to 300 MHz)
  • 8 metres (39.9 to 40.7 MHz), Republic of Ireland, Slovenia and South Africa. Beacons in UK and Denmark
  • 6 metres (50 to 52/54 MHz)
  • 5 metres (59.5 to 60.1 MHz), Republic of Ireland. The Beacon in UK
  • 4 metres (69.9 to 70.5 MHz), Some ITU Region 1 countries
  • 2 metres (144 to 146 MHz)
• Ultra High Frequency (UHF) (300 MHz to 3 GHz)
  • 70 cm (430 MHz)
  • 23 cm (1.3 GHz)
  • 13 cm (2.3 GHz)
• Microwave frequencies
  • 9 cm (3.4 GHz)
  • 6 cm (5.7 GHz)
  • 3 cm (10 GHz)
  • 12 mm (24 GHz)
  • 6 mm (47 GHz)
  • 4mm (76 GHz)
  • <2 mm (134 and 247 GHz)

Table of amateur MF and HF bandplans

The following charts show the voluntary bandplans used by amateurs in ITU Region 1. Unlike the US, slots for the various transmission modes are not set by the amateur's license but most users do follow these guidelines.

160 metres

80 metres

60 metres

40 metres