Amateur radio frequency allocations

Amateur radio frequency allocation is done by national telecommunications 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. The modes and types of allocations within each range of frequencies is called a bandplan, and may be set by international agreements, national regulations, or 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.^[1][2]

Band characteristics

Medium frequency

• 160 meters – 1.8-2 MHz (1800–2000 kHz) – Often taken up as a technical challenge; as 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 meters is also known as the "top band". Allocations in this band vary widely from country to country. This band lies just above the commercial AM broadcast band.

High frequency

• 80 meters – 3.5-4 MHz (3500–4000 kHz) – Best at night, with significant daytime signal absorption. Works best in winter due to atmospheric noise in 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. In the US and Canada the upper end of the sub-band from 3600–4000 kHz, permits use of single-sideband voice as well as amplitude modulation, voice; often referred to as 75 meters.
• 60 meters – 5 MHz region – 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 channelized and may require special application. Voice operation is generally in upper sideband mode and in the USA it is mandatory.
• 40 meters – 7.0–7.3 MHz – Considered the most reliable all-season DX band. Popular for DX at night, 40 meters is also reliable for medium distance (1500 km) 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 listener-ship and increasing competition from net based international broadcast services, many 'short wave' services are being shut down leaving the 40 meter band free of other users for amateur radio use.
• 30 meters – 10.1–10.15 MHz – 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 200w 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 meters is a WARC band. "WARC" bands are so called due to the 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 meters – 14.0–14.35 MHz – Considered the most popular DX band; usually most popular during daytime. QRP operators recognize 14.060 MHz as their primary calling frequency in that band. Users of the PSK31 data mode tend to congregate around 14.071 MHz. Analog SSTV activity is centered around 14.230 MHz.
• 17 meters – 18.068–18.168 MHz – Similar to 20m, but more sensitive to solar propagation minima and maxima. 17 meters is a WARC band.
• 15 meters – 21–21.45 MHz – Most useful during solar maximum, and generally a daytime band. Daytime sporadic-E propagation (1500 km) occasionally occurs on this band.
• 12 meters – 24.89–24.99 MHz – Mostly useful during daytime, but opens up for DX activity at night during solar maximum. 12 meters is one of the new WARC bands.
• 10 meters – 28–29.7 MHz – 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. During the late spring and most of the summer, regardless of sunspot numbers, afternoon short band openings into small geographic areas of up to 1500 km occur due to Sporadic-E propagation. "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 meters all the way up to occasional 2 meter openings. FM operations are normally found at the high end of the band (Also repeaters are in the 29.5 - 29.7 MHz segment in a lot of countries).

Propagation Characteristics above HF

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 VHF signal transmitted from a hand-held portable will typically travel about 5-10 km depending on terrain. With a low power home station and a simple antenna, range would be around 50 km. With a large antenna system like a long yagi, and higher power (typically 100 or more watts) contacts of around 1000 km using the CW (Morse code) and SSB (Single Side Band) modes are common. Ham operators seek to exploit the limits of the frequencies usual characteristics looking to learn, understand and experiment with the limits of these enhanced propagation modes. They also seek to take advantage of "band openings" where due to natural occurrences in the atmosphere and ionosphere radio transmission distances can extend well over their normal range. Many hams listen for hours hoping to take advantage of these occasional extended propagation 'openings'.

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 meter amateur band falls into this category, often called 'The Magic Band', 6 meters will often 'open up' from one small area into another small geographic area 1000–1700 km away during the spring and early summer months. This phenomenon occurs during the fall months, although not as often.

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/foggy days but it also causes VHF/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 kilometers due to these unique weather conditions. For example: The longest distance reported contact due to tropospheric refraction on 2 meters is 4754 km 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 6000 km.^[3]

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, 4 and very rarely on 2 meters (high band VHF) during extreme peaks in the 11 year sunspot cycle. The longest terrestrial contact ever reported on 2 meters (146mhz) was between a station in Italy and a station in South Africa, a distance of 7784 km, using 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 2500–3000 km within either side of the equator.^[4]

Other less frequently used modes are tropospheric scatter, moon bounce and Aurora Borealis (Northern Lights) and amateur radio satellite.

Using relatively high power and a high gain antenna, 'Tropo-scatter' (water droplets and dust particles can refract a VHF/UHF signal over the horizon) propagation will give marginal enhanced over-the-horizon VHF and UHF communications over several hundred kilometers. During the 1970s commercial 'scatter site' operators using huge parabolic antennas and high power used this mode successfully for telephone communications services into remote Alaska and Canadian northern communities. Satellite, buried fiber optic and terrestrial microwave access have relegated 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.

Moon Bounce: Using moderately high power (more than 500 watts) and a fairly large antenna, amateurs do successfully communicate by bouncing their signals off the surface of the moon. 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. Moon bounce communications use either digital modes, for example JT65, designed for working with weak signals, or CW Morse code.

Aurora: An intense solar storm causing aurora borealis (Northern Lights) will also provide occasional HF-low band 6 meter VHF propagation enhancement. Aurora only occasionally affects 2 meters. 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 though the station you are talking to is east or west of you. Most noticeable in the northern latitudes above 45 degrees.

Satellite: Not really a propagation mode, but an active repeater system. Satellites have been highly successful in providing VHF/UHF/SHF users 'propagation' beyond the horizon. The ISS which has amateur radio repeaters and radio location services on board is a good example. Amateurs have also sponsored the launch of dozens of communications satellites since the 1970s. These satellites are usually known as OSCARs (Orbiting Satellite Carrying Amateur Radio).

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.

See also slow-scan television.

Below the MW broadcast band

See also 500 kHz and 2200 meters

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 the 500 kHz band is generally no longer used for regular marine communications, some countries permit experimental amateur radio radiotelegraph operations in that band. Many countries, however, continue to restrict this frequency which was historically reserved for distress calls.^[5] The 2200-meter band is available for use in several countries, and the 2007 World Radiocommunication Conference (WRC-07) made it a worldwide amateur allocation. Before the introduction of the 2200-meter band in the UK in 1998, operation on the even lower frequency of 73 kHz had been allowed between 1996 and 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 meters (135.7 kHz to 137.8 kHz)
• Very High Frequency (VHF) (30 to 300 MHz)
  • 4 metres (70 to 70.5 MHz), UK and some other ITU Region 1 countries

Table of Amateur MF and HF Bandplans

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

160 Metres

160 Metres		1810 1838	1838 1840	1840 1843	1843 2000
IARU Region 1
IARU Region 2	1800–1840
IARU Region 3	1800–1840
Note: Region 2 QRP/DX window is 1830-1850

80 Metres

80 Metres	3500 3580	3580 3600	3600 3620	3620 3800
IARU Region 1

60 Metres

60 Metres	5258.5		5278.5		5288.5		5366.5		5371.5		5398.5		5403.5
United Kingdom
Note: 60 Meter emissions are limited to UK NoV-endorsed Full licence holders only in 3 kHz channels with the specified lower frequency limits, 200 watts Note: There are now 11 channels allocated in the UK, see the 60 Metres article for full details

60 Metres - Norway and Denmark

60 Metres	start		5310.0		5335.0		5355.0		5375.0		5403.5		end
Norway  Denmark	5260.0 5250.0		CW calling		QRP		Digimode		Nat. Call USB		Int. Call USB		5410.0 5450.0
Note: 60 Meter band in Norway is 5260 – 5410 kHz, in Denmark 5250 – 5450 kHz. Danish stations have to apply for a special research-license and are limited to 1 kW ERP. Both countries can use VFO/allmode.

40 Metres

40 Metres	7000 7040	7040 7050	7050 7060	7060 7100	7100 7200	7200 7300
IARU Region 1
As of March, 2009, 7100-7200 were allocated to Amateur radio on a primary basis by ITU. Yet, there are countries that haven't yet expanded their national Amateur radio service bandplan to cover that portion. In ITU region 2, 7200-7300 is allocated to amateur radio service as secondary.

30 Metres

30 Metres	10100 10140	10140 10150
IARU Region 1

20 Metres

20 Metres	14000 14070	14070 14099	B	14101 14350
IARU Region 1

17 Metres

17 Metres	18068 18095	18095 18109	B	18111 18168
IARU Region 1

15 Metres

15 Metres	21000 21070	21070 21110	21110 21120	21120 21149	B	21151 21450
IARU Region 1

12 Metres

12 Metres	24890 24915	24915 24929	B	24931 24990
IARU Region 1

10 Metres

10 Metres	28000 28070	28070 28190	B	28225 29200	29200 29300	29300 29510	29510 29700
IARU Region 1						Satellite D/L

Key

	= CW and data (<200 Hz bandwidth)
	= CW, RTTY and data (< 500 Hz Bandwidth)
	= CW, RTTY, data, NO SSB (<2.7 kHz)
	= CW, phone and image (<3 kHz bandwidth) SECONDARY
	= CW, phone and image (<3 kHz bandwidth)
	= CW, data, packet, FM, phone and image (<20 kHz bandwidth)
	= CW, RTTY, data, test, phone and image
	= Reserved for satellite downlink
	= Reserved for beacons

ITU Region 2

ITU region 2 consists of the Americas, including Greenland. The frequency allocations for United States hams in ITU Region 2 are:

ITU band	Band name	Frequencies (MHz)
		Lower end	Upper end
5 - LF	2200 meters	135.7 kHz	137.8 kHz
6 - MF	160 meters	1.8 MHz	2.0 MHz
7 - HF	80 meters	3.5	4.0
	60 meters	Channelized - 5.332, 5.348, 5.358.5, 5.373, 5.405 MHz, modes see below )
	40 meters	7.0	7.3
	30 meters	10.1	10.15
	20 meters	14	14.35
	17 meters	18.068	18.168
	15 meters	21	21.45
	12 meters	24.89	24.99
	10 meters	28	29.7
8 - VHF	6 meters	50	54
	2 meters	144	148
	1.25 meters	219	220
		222	225
9 - UHF	70 centimeters	420	450
	33 centimeters	902	928
	23 centimeters	1240	1300
	13 centimeters	2300	2310
		2390	2450
10 - SHF	9 centimeters	3300	3500
	5 centimeters	5650	5925
	3 centimeters	10000	10500
	1.2 centimeters	24000	24250
11 - EHF	6 millimeters	47000	47200
	4 millimeters	75500	81000
	2.5 millimeters	122500	123000
	2 millimeters	134000	141000
	1 millimeter	241000	250000

(ARRL 60-Meter Operations

Regarding 60-meter band, Effective 5 March 2012 the FCC has permitted CW, USB, and certain digital modes on these frequencies. The National Telecommunications and Information Administration (NTIA) is the primary user of the 60-meter band. The FCC Report and Order permits the use of digital modes that comply with emission designator 60H0J2B, which includes PSK31 as well as any RTTY signal with a bandwidth of less than 60 Hz. The Report and Order also allows the use of modes that comply with emission designator 2K80J2D, which includes any digital mode with a bandwidth of 2.8 kHz or less whose technical characteristics have been documented publicly, per Part 97.309(4) of the FCC Rules. Such modes would include PACTOR I, II or III, 300-baud packet, MFSK, MT63, Contestia, Olivia, DominoEX and others. On 60 meters hams are restricted to only one signal per channel and automatic operation is not permitted. In addition, the FCC continues to require that all digital transmissions be centered on the channel-center frequencies, which the Report and Order defines as being 1.5 kHz above the suppressed carrier frequency of a transceiver operated in the Upper Sideband (USB) mode. As amateur radio equipment displays the carrier frequency, it is important for operators to understand correct frequency calculations for digital "sound-card" modes to ensure compliance with the channel-center requirement.

The ARRL has a detailed band plan for US hams showing allocations within each band.

RAC has a chart showing the frequencies available to amateurs in Canada.

Table of Amateur MF and HF Allocations in the United States and Canada

160 m	1800–2000
Canada
United States	1800 2000
General, Advanced, Extra

80 / 75 m	3500 - 4000
Canada
United States	3500 3525	3525 3600	3600 3700	3700 3800	3800 4000
Novice / Technician
General
Advanced
Extra

60 m	5330 - 5406
Canada		5332.0		5348.0		5358.5		5373.0		5405.0
United States	5330.5		5346.5		5357.0		5371.5		5403.5
General, Advanced, Extra
Basic with Honours or Code / Advanced
Note: US licensees operating 60 m are limited to 100 watts PEP ERP relative to a 1/2 wave dipole, on the carrier frequencies indicated on this chart. Canadian operators are restricted to 100 watts PEP, 2.8kHz bandwidth, and the following emissions modes and designators: telephony (2K80J3E), data (2K80J2D), RTTY (60H0J2B) and CW (150HA1A).[6]

40 m	7000 - 7300
Canada
United States	7000 7025	7025 7125	7125 7175	7175 7300
Novice / Technician
General
Advanced
Extra

30 m	10100 10150
Canada
United States
Note: US limited to General, Advanced and Extra licensees; 200 watts PEP

20 m	14000 - 14350
Canada
United States	14000 14025	14025 14150	14150 14175	14175 14225	14225 14350
General
Advanced
Extra

17 m	18068 - 18168
Canada
United States	18068 18110	18110 18168
General, Advanced, Extra

15 m	21000 - 21450
Canada
United States	21000 21025	21025 21200	21200 21225	21225 21275	21275 21450
Novice / Technician
General
Advanced
Extra

12 m	24890 - 24990
Canada
United States	24890 24930	24930 24990
General, Advanced, Extra

10 m	28000 - 29700
Canada
United States	28000 28300	28300 28500	28500 29700
Novice / Technician
General, Advanced, Extra
Note: The 10 meter table is one-third scale, relative to the other tables

Key

	= CW, RTTY and data (US: < 1 kHz Bandwidth)
	= CW, RTTY, data, MCW, phone (AM and SSB) and image (narrow band sstv modes only)
	= CW, phone and image
	= CW and SSB phone (US: Novice/Technician 200 watts PEP only)
	= CW, RTTY, data, phone and image
	= CW (US: Novice/Technician 200 watts PEP only)
	= CW, Upper sideband suppressed carrier phone, 2.8 kHz bandwidth (2K80J3E) data (60H0J2B and 2K80J2D), 100 watts ERP referenced to 1/2 wave dipole
	= CW, RTTY and data (US: < 1 kHz Bandwidth, Novice/Technician 200 watts PEP)

ITU Region 3

ITU region 3 consists of Australia, Indonesia, Japan, New Zealand, the South Pacific, and Asia south of Siberia. The IARU frequency allocations for hams in ITU Region 3 are:

The Region 3 Bandplan ^[7] is as follows:

ITU band	Band name	Frequencies (MHz)
		Lower end	Upper end
5 - LF	2200 meters	135.7 kHz	137.8 kHz
6 - MF	630 meters	472 kHz	479 kHz
	160 meters	1.8	2.0
7 - HF	80 meters	3.5	3.9
	40 meters	7.0	7.3
	30 meters	10.1	10.157.3
	20 meters	14	14.35
	17 meters	18.068	18.168
	15 meters	21	21.45
	12 meters	24.89	24.99
	10 meters	28	29.7
8 - VHF	6 meters	50	54
	2 meters	144	148
9 - UHF	70 centimeters	430	450
	23 centimeters	1240	1300

Bands above 1300 MHz: Societies should consult with the amateur satellite community for proposed satellite operating frequencies before deciding local bandplans above 1300 MHz.

Not all Member Unions follow this plan. As an example, the ACMA does not allow Australian Amateurs to use 3.700 MHz to 3.768 MHz and 3.800 MHz to 3.900 MHz, allocating this region to Emergency and Ambulatory services (Allocations can be found conducting a search of the ACMA Radcomms register . )

The Wireless Institute of Australia has charts for Amateur frequencies for Australia.

The New Zealand Association of Radio Transmitters (NZART) has charts for Amateur frequencies and repeater lists for New Zealand.

The Japanese have charts for Amateur frequencies in Japan

Space Operations

Radio amateurs may engage in satellite and space craft communications; however, the frequencies allowed for such activities are allocated separately from more general use radio amateur bands.

Under the International Telecommunication Union's rules, all amateur radio operations may only occur within 50 kilometres (31 mi) of the Earth's surface. As such, the Amateur Radio Service is not permitted to engage in satellite operations; however, a sister radio service, called the Amateur Satellite Service, exists which allows satellite operations for the same purposes as the Amateur Radio Service. In most countries, an amateur radio license conveys operating privileges in both services, and in practice, the legal distinction between the two services is transparent to the average licensee. The primary reason the two services are separate is to limit the frequencies available for satellite operations. Due to the shared nature of the amateur radio allocations internationally, and the nature of satellites to roam worldwide, the ITU does not consider all amateur radio bands appropriate for satellite operations. Being separate from the Amateur Radio Service, the Amateur Satellite Service receives its own frequency allocations. All the allocations are within amateur radio bands, and with one exception, the allocations are the same in all three ITU regions. Some of the allocations are limited by the ITU in what direction transmissions may be sent (EG: "Earth-to-space" or up-links only).

All amateur satellite operations occur within the allocations tabled below, except for AO-7, which has an up-link from 432.125 MHz to 432.175 MHz.

International amateur satellite frequency allocations
Range	Band	Letter^1	Allocation[8]	Preferred sub-bands^2	User status[8]	Notes[8]
HF	40 m		7.000 MHz - 7.100 MHz		Primary
	20 m		14.000 MHz - 14.250 MHz		Primary
	17 m		18.068 MHz - 18.168 MHz		Primary	Entire amateur radio band
	15 m	H	21.000 MHz - 21.450 MHz		Primary	Entire amateur radio band
	12 m		24.890 MHz - 25.990 MHz		Primary	Entire amateur radio band
	10 m	A	28.000 MHz - 29.700 MHz	29.300 MHz - 29.510 MHz	Primary	Entire amateur radio band
VHF	2 m	V	144.000 MHz - 146.000 MHz	145.800 MHz - 146.000 MHz	Primary
UHF	70 cm	U	435.000 MHz - 438.000 MHz		NIB^3
	23 cm	L	1.260 GHz - 1.270 GHz		NIB^3	Only uplinks allowed
	13 cm	S	2.400 GHz - 2.450 GHz	2.400 GHz - 2.403 GHz	NIB^3
SHF	9 cm	S2	3.400 GHz - 3.410 GHz		NIB^3	Not available in ITU region 1.
	5 cm	C	5.650 GHz - 5.670 GHz		NIB^3	Only uplinks allowed
			5.830 GHz - 5.850 GHz		Secondary	Only downlinks allowed
	3 cm	X	10.450 GHz - 10.500 GHz		Secondary
	1.2 cm	K	24.000 GHz - 24.050 GHz		Primary
EHF^4	6 mm	R	47.000 GHz - 47.200 GHz		Primary	Entire amateur radio band
	4 mm		76.000 GHz - 77.500 GHz		Secondary
			77.500 GHz - 78.000 GHz		Primary
			78.000 GHz - 81.000 GHz		Secondary
	2 mm		134.000 GHz - 136.000 GHz		Primary	Entire amateur radio band
			136.000 GHz - 141.000 GHz		Secondary
	1 mm		241.000 GHz - 248.000 GHz		Secondary	Entire amateur radio band
			248.000 GHz - 250.000 GHz		Primary
^1 AMSAT band letters. Not all bands have been assigned a letter by AMSAT. ^2 For some allocations, satellite operations are predominantly concentrated in a sub-band of the allocation. ^3 Footnote allocation. Use is only allowed on a non-interference basis to other users, as per ITU footnote 5.282.[8] ^4 No amateur satellite operations have yet occurred at EHF; however, AMSAT's P3E is planned to have an R band down-link.

See also

• List of amateur radio frequency bands in India
• An attempt for a unified amateur radio bandplan: http://xmlbandplan.org

References

1. "Frequency Bands". ARRL. Archived from the original on 4 June 2011. Retrieved 27 June 2011.
2. Larry D. Wolfgang et al., (ed), The ARRL Handbook for Radio Amateurs, Sixty-Eighth Edition , (1991), ARRL, Newington CT USA ISBN 0-87259-168-9 Chapter 37
3. http://df5ai.net/ArticlesDL/HadleyCellProp.pdf
4. http://sektion-vhf.ssa.se/dxrecord/dxrec.htm
5. http://www.radiomarine.org/gallery/show?keyword=USNAVY&panel=pab1_7
6. http://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf10623.html
7. http://www.jarl.or.jp/iaru-r3/
8. "FCC Online Table of Frequency Allocations" (PDF). 47 C.F.R. Federal Communications Commission. 2 June 2011. Retrieved 4 August 2011.