Summary

4 metres is an Amateur Radio frequency band in the lower Very High Frequency spectrum. Traditionally only allocated in a small number of countries in Europe and Africa, the decline in VHF television broadcasts, movement away from the old Eastern European VHF FM broadcast band and migration of commerical stations to higher frequencies have led to slow but steady growth in the number of countries where 4 metre operation is permitted. Mrs. ... Very high frequency (VHF) is the radio frequency range from 30 MHz (wavelength 10 m) to 300 MHz (wavelength 1 m). ... Very high frequency (VHF) is the radio frequency range from 30 MHz (wavelength 10 m) to 300 MHz (wavelength 1 m). ... Eastern Europe is, by convention, a region defined geographically as that part of Europe covering the eastern part of the continent. ... Frequency modulation (FM) is a form of modulation which represents information as variations in the instantaneous frequency of a carrier wave. ...

It ranges from 70 to 70.5 MHz in the United Kingdom, with other countries generally having a smaller allocation within this window. The 4 Metre band shares many characteristics with the neighbouring 6 metres band. However, as it is somewhat higher in frequency it does not display the same propagation mechanisms via the F2 ionospheric layer normally seen at HF which occasionally appear in 6 metres, leastwise not at temperate latitudes. However, Sporadic E is common on the band in summer, toprospheric propagation is marginally more successful than on 6 metres, and propagation via the Aurora Borealis and meteor scatter is highly effective. The 4 metre band has a unique character, because very few countries have an allocation there, very little commercial equipment is available, and therefore most amateurs active on the band are interested in home construction. As a result there is a lot of camaraderie on the band and long ragchews are the norm, as long as there is some local activity. A megahertz (MHz) is one million (106) hertz, a measure of frequency. ... The word propagation can mean: Multiplication or increase, as by natural reproduction. ... The ionosphere is the part of the atmosphere that is ionized by solar radiation. ... HF or Hf might be an acronym or abbreviation for: High frequency Radio hafnium, a chemical element the chemical formula for Hydrofluoric acid Historisk-filosofisk fakultet, abbr. ... TV DX and FM DX are two terms, customarily grouped together, that mean distant reception of TV and FM radio stations, respectively. ... Aurora borealis Polar aurorae are optical phenomena characterized by colorful displays of light in the night sky. ... A burst of meteors A meteor is the visible path of a meteoroid that enters the Earths (or another bodys) atmosphere, commonly called a shooting star or falling star. ...

Some low power FM commerical equipment is available for the band, although it is of relatively simple specifications as generally suitable for communication of up to around 50 kilometres or so with simple antennas, in the Sporadic E seasons communication around Europe is possible with such equipment. A limited number of transceivers were purpose built for amateurs on this band, while converted Private Mobile Radio equipment is in widespread use. For more reliable DX performance, however, at least some equipment must be home constructed, and the most popular route is usually to use a 10 metre or 6 metre commerically made transceiver followed by a home built transverter. To help compare different orders of magnitude this page lists lengths between 10 and 100 km (104 to 105 m). ... DX can refer to: a common telegraphic abbreviation that stood for a signal that travelled a very long distance. ... The 10 meter amateur radio band is the highest of the High Frequency or HF bands. ... A transceiver is a device that has a transmitter and receiver which is combined into a one unit. ... A transverter is a radio frequency device that consists of an upconverter and a downconverter in one unit. ...

In most countries, the maximum power permitted on the band is lower than in other allocations, to minimise the possibility of interference with non-amateur services, especially in neighbouring countries.

In some parts of the UK the band is little utilised, while in others, notably Belfast, Bristol, South Wales, North London and Hertfordshire, there is extensive local FM operation. There is considerable AM activity in the Dublin area. As band occupancy is relatively low, FM operation tends to take place on the calling frequency, 70.450 MHz, and AM operation on that calling frequency, 70.260 MHz. In the UK, the band is also used considerably for emergency communications, Internet Radio Linking Project links (IRLP), data links and low powered remote control. Belfast (Béal Feirste in Irish) is the second-largest city in Ireland. ... Bristol is an English city and county and one of the three administrative centres of South West England (the others being Plymouth and Exeter). ... South Wales is an area of Wales bordered by England and the Bristol Channel to the East and South, and Mid Wales and West Wales to the North and West. ... North London is that part of London which is north of the River Thames. ... Hertfordshire (pronounced Hartfordshire and abbreviated as Herts) is an inland county in the United Kingdom, officially part of the East of England Government region. ... Amplitude modulation (AM) is a form of modulation in which the amplitude of a carrier wave is varied in direct proportion to that of a modulating signal. ... Dublin (Irish: Baile Átha Cliath), is the capital and largest city of the Republic of Ireland, located near the midpoint of Irelands east coast, at the mouth of the River Liffey and at the centre of the Dublin region. ... The Internet Radio Linking Project is a project within general amateur radio. ...

In continental Europe the band is still primarily used for more serious DX operation. Cross-band working with 6 metres or 10 metres is common to make contacts countries where the band is not allocated.

While Sporadic E permits Europe wide communication, it can be a mixed blessing as the band is still used for wide bandwidth, high power FM broadcasting on the OIRT FM band in a declining number of Eastern European countries. Although this is has lessened in recent years, it can still cause considerable interference to both local and DX operation. Bandwidth is a measure of frequency range. ... In most of the world, the FM broadcast band, used for broadcasting FM radio stations, goes from 87. ...

As of 2005, no communication has taken place on the 4 metre band between Europe and Southern Africa, although theoretically this ought to be possible by stations with amateur power and antenna sizes around the equinoxes. It is to be hoped that the increasing availability of the band in Mediterranean countries, where the trans-equatorial path is less difficult than from the bands traditional strongholds in Britain and Ireland, might spur such interest. 2005 is a common year starting on Saturday of the Gregorian calendar. ... World map showing Europe (geographically) When considered a continent, Europe is the worlds second-smallest continent in terms of area, with an area of 10,600,000 km² (4,140,625 square miles), making it larger than Australia only. ... Categories: Africa geography stubs | Southern Africa ... In astronomy, an equinox is defined as the moment when the sun reaches one of two intersections between the ecliptic and the celestial equator. ... The Mediterranean Sea is an intercontinental sea positioned between Europe to the north, Africa to the south and Asia to the east, covering an approximate area of 2. ...

In November 2005, the 4 metre band was allocated in the following countries:
Ongoing events • 2005 Kuomintang visits to Mainland • Bill C-38 (Canada gay marriage) • German Visa Affair 2005 • Expo 2005 in Aichi, Japan • Fuel prices • Election of OAS Secretary General • Stanislav Gross scandal in Czech republic Upcoming events Deaths in May May 3: Jagjit Singh Aurora May 3: Don Canham May...

• "traditional" 4 metre countries - the United Kingdom, its dependencies of the Isle of Man, Guernsey, Jersey, Gibraltar and the Sovereign Base Areas on Cyprus, in the Republic of Cyprus, the Republic of Ireland, South Africa and Namibia.
  
• "new" 4 metre countries - Croatia, Denmark, the Faroe Islands, Greenland, Slovenia and Somalia.
  
• "possible" 4 metre countries - Romania and Serbia and Montenegro, where amateurs have been active in the Sporadic E season and apparently have received informal permission from their communications regulators to operate on a trial basis, although no official publiciation to that effect has been made.

There are active campaigns to secure 4 metre privileges in Italy, Greece, Sweden, Portugal and Finland. The UK Sovereign Base Areas are those British military base areas located in countries formerly ruled by the United Kingdom which were retained by it and not handed over when those countries attained independence. ...

Band Plans

RSGB 70 MHz Band Plan

70.000 - 70.050    The Radio Society of Great Britain (RSGB) is the UKs recognised national society for radio amateurs. ...	Beaconsonly	70.030	Personal Beacons
70.050 - 70.250	Narrow Band modes	70.085		PSK31 centre of activity
		70.185	Cross-band activity centre
		70.200	SSB/CW calling
70.250 - 70.300	All modes	70.260	AM/FM calling frequency
70.300 - 70.500	All modes channelised operation with 12.5 kHz spacing	70.300	RTTY/fax calling/working
		70.3125	Digital modes
		70.325	Digital modes
		70.3375	Digital modes
		70.350	Digital modes
		70.3625	Digital modes
		70.375	FM Simplex
		70.3785	Internet voice gateway
		70.400	FM Simplex
		70.4125	Internet voice gateway
		70.425	FM Simplex
		70.4375	Digital modes
		70.450	FM Calling frequency
		70.4625	Digital modes
		70.475	FM simplex
		70.4875	Digital modes

(Source: The Four Metres Website)

Common Uses of 4 Meters

• FM Simplex
• AM Simplex
• Packet radio
• SSB voice operation
• Morse Code (CW) operation
• DX

Frequency modulation (FM) is a form of modulation which represents information as variations in the instantaneous frequency of a carrier wave. ... A simplex communication system is one where all signals flow in one direction. ... Amplitude modulation (AM) is a form of modulation in which the amplitude of a carrier wave is varied in direct proportion to that of a modulating signal. ... A packet is the fundamental unit of information carriage in all modern computer networks. ... Single-sideband modulation (SSB) is a refinement of the technique of amplitude modulation designed to be more efficient in its use of electrical power and bandwidth. ... 1922 Chart of the Morse Code Letters and Numerals Morse Code is a method for transmitting information, using standardized sequences of short and long marks or pulses -- commonly known as dots and dashes -- for the letters, numerals and special characters of a message. ... DX can refer to: a common telegraphic abbreviation that stood for a signal that travelled a very long distance. ...

External links

The Four Metres Website