70-centimeter band: Difference between revisions

{{Use dmy dates|date=JulyOctober 20132023}}

The '''70-centimeter''' or '''440 &nbsp;MHz''' band is a portion of the [[Ultra high frequency|UHF]] radio spectrum internationally allocated to [[amateur radio]] and [[amateur satellite]] use. The [[International Telecommunication Union|ITU]] amateur radio allocation is from 430 to 440&nbsp;MHz; however, some countries, such as the United States, allocate hams 420 to 450&nbsp;MHz. Depending Amateuron satellitesthe are only allocated a small portion ofcountry the band, 435 to 438&nbsp;MHz, on a non-interference basis. The band is usually shared with other radio services, most(in commonlyUnited States with government [[radar]] systems, such as [[PAVE PAWS]]).<ref name=NTIA-Feduse />

70 centimeters is the mosta popular UHF ham band due to the ready availability of equipment in both new and used markets. Most amateurs operating on 70  cm use either equipment purpose -built for ham radio, or commercial equipment designed for nearby [[land mobile]] frequencies. Amateurs predominatelyusually use the band for [[Frequency modulation|FM]] or digital voice communications through [[repeater]]s (useful for emergency communications), as well narrow band modes (analog and digital) for long-distance communications (called "DX", including [[Earth–Moon–Earth communication|Moon bounce]]). The band is also popular for Amateur Satellite Service. Due to its [[Bandwidth (signal processing)|size]], it's the lowest frequency ham band which can support [[Amateuramateur television]] transmissions.

The band's allocation varies regionally. In the United States,<ref name=US_Allocation>{{cite web|url=http://edocket.access.gpo.gov/cfr_2008/octqtr/pdf/47cfr97.301.pdf|title=§ 97.301 Authorized frequency bands|publisher=The Federal Communications Commission|page=2|format=PDF|date=1 October 2008|accessdateaccess-date=15 November 2009}}</ref> [[Australia]] and [[Trinidad and Tobago]],<ref>{{cite web|url=http://www.tatt.org.tt/linkclick.aspx?fileticket=p-oVvD_2qXg%3d&tabid=98 |title=Trinidad and Tobago Frequency Allocation Table (9 kHz to 1000 GHz) |publisher=The Telecommunications Authority of Trinidad and Tobago |page=154 |format=PDF |date=16 October 2009 |accessdateaccess-date=15 November 2009 |deadurlurl-status=yesdead |archiveurlarchive-url=https://web.archive.org/web/20110721195011/http://www.tatt.org.tt/linkclick.aspx?fileticket=p-oVvD_2qXg%3D&tabid=98 |archivedatearchive-date=21 July 2011 }}. See Footnote TT34.</ref> the band ranges from 420 to 450 [[Megahertz|MHz]] with some geographical limitations. In [[Canada]] and [[Australia]], the band is only 430&ndash;450&nbsp;MHz. In the UK, amateurs are allocated 430&ndash;440&nbsp;MHz. By international treaty between the US and Canada, operation in the portion of the band from 420 to 430&nbsp;MHz is prohibited north of Line A,<ref>{{cite web|url=http://www.fcc.gov/oet/info/maps/canline/canline.html |title=ArchivedOET copy--Frequency Coordination, Canada |accessdateaccess-date=13 September 2009 |deadurlurl-status=yesdead |archiveurlarchive-url=https://web.archive.org/web/20091215034049/http://www.fcc.gov/oet/info/maps/canline/canline.html |archivedatearchive-date=15 December 2009 }}</ref> which runs just south of the Canada–US border from [[Washington (state)|Washington]] state to [[Maine]],<ref>{{cite web |url=https://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&SID=336ab7469b61ecbfa15086dbf1bf2c59&rgn=div5&view=text&node=47:5.0.1.1.6&idno=47#se47.5.97_13 |title=Electronic Code of Federal Regulations, Title 47 → Chapter I → Subchapter D → Part 97 |author=<!--Not stated--> |date=14 November 14, 2017 |website=ecfr.gov |publisher=Federal Communications Commission |access-date=16 November 16, 2017 |quote=FCC Part 97.3a, subsection (30): '''Line A.''' Begins at [[Aberdeen, Washington|Aberdeen, WA]], running by great circle arc to the intersection of 48° N, 120° W, thence along parallel 48° N, to the intersection of 95° W, thence by great circle arc through the southernmost point of [[Duluth, Minnesota|Duluth, MN]], thence by great circle arc to 45° N, 85° W, thence southward along meridian 85° W, to its intersection with parallel 41° N, thence along parallel 41° N, to its intersection with meridian 82° W, thence by great circle arc through the southernmost point of [[Bangor, Maine|Bangor, ME]], thence by great circle arc through the southernmost point of [[Searsport, Maine|Searsport, ME]], at which point it terminates.}}</ref> and east of Line C, which runs from northeast to southeast [[Alaska]].

70-centimeter propagation characteristics lie midway between 2-meter and 33-centimeter (~900&nbsp;MHz) bands. Above 200&nbsp;MHz, as frequency increases, building penetration is reduced.<ref>{{cite book |archiveurlarchive-url= https://web.archive.org/web/20141227232756/http://nashville.dyndns.org:800/wirelessdownloads/propagation/InBuilding/EspeciallyRelevantPapers/Measurement%20of%20RF%20Propagation%20into%20Concrete%20Structures%20over%20the%20Frequency%20Range%20100%20MHz%20ro%203%20GHz.pdf |archivedatearchive-date=27 December 2014 |url= http://nashville.dyndns.org:800/wirelessdownloads/propagation/InBuilding/EspeciallyRelevantPapers/Measurement%20of%20RF%20Propagation%20into%20Concrete%20Structures%20over%20the%20Frequency%20Range%20100%20MHz%20ro%203%20GHz.pdf |title= Wireless Personal Communications : Advances in Coverage and Capacity |chapter= 13 -– Measurement of RF Propagation into Concrete Structures over the Frequency Range 100 MHz to 3 GHz |author= Taylor, Clayborne D. |date=6 November 2012 |pages= 13–14 |quote= measured attenuation above 200 MHz appears to increase with an increase in frequency |ISBNisbn= 978-1-4613-7861-7|display-authors=etal}}</ref> However, smallerSmaller obstacles may also block or reflect the signal. HigherHowever, higher frequencies also present a lower [[noise floor]], making it easier to overcome both natural and artificial interference, especially prevalent in urban environments.

Propagation considerations often take a back seat to channel availability or economic concerns in system planning. One practical concern when comparing the 70-centimeter band to the 2-meter band is that a quarter-wavelength antenna is much less unwieldy at 70 centimeters than it is at 2 meters. Portable antennas for 2 meters are generally continuously loaded coil spring or "[[Rubber ducky antenna|rubber duck]]" types, while on 70 centimeters they can be a full quarter wavelength. The difference can be as much as 8 dB{{Citation needed|date=January 2021}}. The primary advantage of 70 centimeters is that base station antennas of very significant gain (up to 11 dB or so) are practical while 6 dB is about the practical limit on 2m. The extra 5 dB of receive and transmit gain are often critical for long-range communication, particularly for high-power repeaters which can then concentrate all of their power and receive sensitivity at the horizon.

70 centimeters is very close to the third harmonic of 2 meters, which allows sufficiently broadband 2 –meter antennas to be used for 70 centimeters. Antennas specifically designed to work on both bands are common. Also, 2 meters is far enough away from 70 centimeters to make [[diplexer]]s small and simple, making it easy to cross-band [[Radio repeater|repeat]] signals between the two bands with a single dual-band radio.

In some countries, particularly [[Germany]] (until the end of 2008)<ref>[http://www.rc-network.de/magazin/artikel_05/art_05-027/laender/GER.pdf RC-Network.de Fernsteuerfrequenzen für den Modellbau -– Deutschland (Frequency bands for RC modeling -– Germany) -– "Am 31.12.2008 endet die Betriebserlaubnis für Fernsteuerungen im Frequenzbereich 433 MHz!"] {{Webarchive|url=https://web.archive.org/web/20160323031142/http://rc-network.de/magazin/artikel_05/art_05-027/laender/GER.pdf |date=23 March 2016 }} (As of 12/31/2008, RC use of the 433 MHz bands ends in Germany!)</ref> and [[Switzerland]], a portion of the 70&nbsp;cm band overlaps with a secondary frequency allocation for the operation of [[Radio control]] models. In Germany, 33 frequencies were available for RC use,<ref>{{cite web |url=http://www.ukrcc.org/germany.html |title=United Kingdom Radio Control Council: International Frequencies -– Germany |author=<!--Staff writer(s); no by-line.--> |date= |website=UKRCC |publisher=UKRCC |accessdateaccess-date=13 July 2013 |archive-date=4 March 2016 |archive-url=https://web.archive.org/web/20160304034515/http://www.ukrcc.org/germany.html |url-status=dead }}</ref> and in [[Switzerland]], ten frequencies are available.<ref>{{cite web |url=http://www.ukrcc.org/switzerland.html |title=United Kingdom Radio Control Council: International Frequencies -– Switzerland |author=<!--Staff writer(s); no by-line.--> |date= |website=UKRCC |publisher=UKRCC |accessdateaccess-date=13 July 2013 |archive-date=3 March 2016 |archive-url=https://web.archive.org/web/20160303234818/http://www.ukrcc.org/switzerland.html |url-status=dead }}</ref> These frequencies fall within the [[LPD433]] band used by [[Short Range Devices|short range devices]] in Europe.

{{reflist|30em|refs=

|title = 420-450420–450 MHz

|date = March 1, March 2014

|access-date = July 23, July 2019

}}</ref>

*[httphttps://www.iaru.org/wp-content/uploads/12020/301/0/7/13073366/spectrum_requirements_2013Amateur-Services-Spectrum-2020_.pdf Spectrum Requirements for the Amateur and Amateur-satellite ServicesService Spectrum, revisedRevised SeptemberJanuary 20132020]