4-meter band

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The 4-metre (70 MHz) band is an amateur radio frequency band in the lower Very High Frequency (VHF) spectrum.

The 4-metre band has a unique character and because very few countries have an allocation there, very little dedicated commercial amateur equipment is available. Therefore, most amateurs active on the band are interested in home construction or modification of private mobile radio (PMR) equipment. 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.

History

Lua error in package.lua at line 80: module 'strict' not found. Before World War II, British radio amateurs had been allocated a band at 56 MHz. After the war ended, they were allocated the 5-metre band (58.5 MHz to 60 MHz) instead. This only lasted until 1949, as by then the 5-metre band had been earmarked for BBC Television broadcasts.

In 1956, after several years of intense lobbying by the Radio Society of Great Britain (RSGB), the 4-metre band was allocated to British radio amateurs as a replacement for the old 5-metre band allocation. For several years the 4-metre band allocation was only 200 kHz wide—from 70.2 MHz to 70.4 MHz. It was later extended to 70.025 MHz to 70.7 MHz. The band limits were subsequently moved to today's allocation of 70.0 MHz to 70.5 MHz.

Allocations

File:VHF Usage 40 to 100mhz.png
A chart showing how Television channel frequencies in various countries relate to the 4 metre amateur band.

In addition to the traditional users (United Kingdom, Gibraltar and the British Military Bases in Cyprus), an increasing number of countries in Europe and Africa have also allocated the 4-metre band to radio amateurs as a result of the decline in VHF television broadcasts on the 4-metre band. Movement away from the old Eastern European VHF FM broadcast band and migration of commercial stations to higher frequencies have led to slow but steady growth in the number of countries where 4-metre operation is permitted.

Whilst not formally allocated at an ITU or Regional level, in Europe CEPT now recognises the increased access to 70 MHz by radio amateurs with footnote 'EU9' which has helped underpin further growth. In July 2015 CEPT updated this footnote to fully recognise it as a formal secondary allocation:

"EU9: CEPT administrations may authorise all or parts of the band 69.9-70.5 MHz to the amateur service on a secondary basis."

In practice this ranges from 70 MHz to 70.5 MHz in the United Kingdom, with other countries generally having a smaller allocation within this window. 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. A table with national and regional allocations is pusblished and regularly updated on the Four Metres Website.[1]

Propagation

The 4-metre band shares many characteristics with the neighbouring 6-metre 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, tropospheric propagation is marginally more successful than on the 6-metre band, and propagation via the Aurora Borealis and meteor scatter is highly effective.

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 has lessened in recent years, it can still cause considerable interference to both local and long distance (DX) operation.

First ever transequatorial propagation (TEP) contact on 70 MHz took place on 28 March 2011 between Leonidas Fiskas, SV2DCD, in Greece and Willem Badenhorst, ZS6WAB, in South Africa.[2][3]

Equipment and power

Access to the 4-metre band has always been limited by access to suitable 4-metre transceivers. A limited number of transceivers were purposely built for amateurs on this band while converted Private Mobile Radio equipment is in widespread use e.g. Phillips FM1000 and the Ascom SE550. Some low power FM commercial equipment is available for the band although it is of relatively simple specifications as generally suitable for communication of up to around 50 kilometres (31 mi) or so with simple antennas.

In the Sporadic E seasons communication around Europe is possible with such equipment. Currently, the only Japanese-made, "mass-market" amateur radio transceiver to cover the Four metre band as standard is the Icom IC-7100, previously there was the UK specification Yaesu FT-847 which was discontinued in 2005. As a result, many 4-metre users gain access to the band by using converted "Low band" VHF ex-PMR (Private Mobile Radio) transceivers but invariably these only have either AM or FM and those users who prefer to have a multi-mode capability but can't afford a second hand Yaesu FT-847 normally use transverters, either purposely built home builds or sometimes even converted 6-metre or 2-metre versions.

In recent years there have been extensive imports of Chinese PMR transceivers such as the Wouxun KG-699E 4m (66–88 MHz) and KG-UVD1P1LV DUAL BAND (TX/RX 66–88 MHz / 136–174 MHz) Handheld Transceiver to Western countries mainly so far in the UK and mainland Europe. Qixiang Electronics, the makers of the AnyTone and MyDel transceivers, have exported the AnyTone 5189 PMR 4m Mobile, and the AnyTone 3308 Handheld (66–88 MHz) transceivers from China to the UK and to Europe. Both Transceivers have been selling extensively well in the UK and in Europe.

Recently (2014) a Monoband Multimode 70 MHz SSB/CW transceiver is released by NOBLE RADIO. Their website is www.nobleradio.eu. At of this moment (October 2014) their 70 MHz transceiver is worldwide the only one available.

Activity

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.

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

Countries in which operation is permitted

File:Amateur-radio-regions-with-4m-allocation.svg
Red regions designate areas with known allocations. Blue regions designate areas with experimental allocations.

Countries with a known band allocation:[4]

Countries with past or current experimental operation

In "experimental" countries, authorities authorized amateur radio experiments on the band for a limited period of time.

Other

  • United States has one experimental transmitter in Virginia transmitting CW on 70.005 MHz. Call sign is WE9XFT.
  • Glen Zook, K9STH, the Head Moderator of QRZ.com and a longtime magazine writer on VHF related topics, filed a petition with the U.S. Federal Communications Commission on 27 January 2010 to create a new U.S. 4-Metre amateur radio allocation at 70 MHz to parallel those in Europe and other parts of the world. [21] This petition was subsequently rejected by the FCC.

Common uses of the 4-metre band

References

  1. ↑ Metres Website, International 70 MHz allocations
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External links

International amateur radio frequency allocations
Range Band ITU Region 1 ITU Region 2 ITU Region 3
LF 2200 m 135.7 kHz – 137.8 kHz
MF 600 m 472 kHz – 479 kHz
160 m 1.810 MHz – 1.850 MHz 1.800 MHz – 2.000 MHz
HF 80 / 75 m 3.500 MHz – 3.800 MHz 3.500 MHz – 4.000 MHz 3.500 MHz – 3.900 MHz
60 m 5.3515 MHz – 5.3665 MHz
40 m 7.000 MHz – 7.200 MHz 7.000 MHz – 7.300 MHz 7.000 MHz – 7.200 MHz
30 m2 10.100 MHz – 10.150 MHz
20 m 14.000 MHz – 14.350 MHz
17 m2 18.068 MHz – 18.168 MHz
15 m 21.000 MHz – 21.450 MHz
12 m2 24.890 MHz – 24.990 MHz
10 m 28.000 MHz – 29.700 MHz
VHF 6 m 50.000 MHz – 52.000 MHz1 50.000 MHz – 54.000 MHz
4 m1 70.000 MHz – 70.500 MHz N/A
2 m 144.000 MHz – 146.000 MHz 144.000 MHz – 148.000 MHz
1.25 m N/A 220.000 MHz – 225.000 MHz N/A
UHF 70 cm 430.000 MHz – 440.000 MHz 430.000 – 440.000 MHz
(420.000 – 450.000 MHz)3
33 cm N/A 902.000 MHz – 928.000 MHz N/A
23 cm 1.240 GHz – 1.300 GHz
13 cm 2.300 GHz – 2.450 GHz
SHF 9 cm 3.400 GHz – 3.475 GHz3 3.300 GHz – 3.500 GHz
5 cm 5.650 GHz – 5.850 GHz 5.650 GHz – 5.925 GHz 5.650 GHz – 5.850 GHz
3 cm 10.000 GHz – 10.500 GHz
1.2 cm 24.000 GHz – 24.250 GHz
EHF 6 mm 47.000 GHz – 47.200 GHz
4 mm3 75.500 GHz1 – 81.500 GHz 76.000 GHz – 81.500 GHz
2.5 mm 122.250 GHz – 123.000 GHz
2 mm 134.000 GHz – 141.000 GHz
1 mm 241.000 GHz – 250.000 GHz
THF Sub-mm Some administrations have authorized spectrum for amateur use in this region.

1 This is not mentioned in the ITU's Table of Frequency Allocations, but individual administrations may make allocations under Article 4.4 of the ITU Radio Regulations. See the appropriate Wiki page for further information.
2 HF allocation created at the 1979 World Administrative Radio Conference. These are commonly called the "WARC bands".
3 This includes a currently active footnote allocation mentioned in the ITU's Table of Frequency Allocations. These allocations may only apply to a group of countries.
See also: Radio spectrum · Electromagnetic spectrum
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