ultra high frequency
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Ultra high frequency (UHF) is the
ITU 260px, ITU Monument, Bern The International Telecommunication Union is a specialized agency of the United Nations responsible for all matters related to information and communication technologies Information and communications technology ...
designation for
radio frequencies Radio frequency (RF) is the oscillation Oscillation is the repetitive variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. The term '' vibration'' is prec ...
in the range between 300 
megahertz The hertz (symbol: Hz) is the unit Unit may refer to: Arts and entertainment * UNIT, a fictional military organization in the science fiction television series ''Doctor Who'' * Unit of action, a discrete piece of action (or beat) in a theatric ...
(MHz) and 3 
gigahertz The hertz (symbol: Hz) is the SI derived unit, derived unit of frequency in the International System of Units (SI) and is defined as one cycle (geometry), cycle per second. It is named after Heinrich Hertz, Heinrich Rudolf Hertz, the first per ...
(GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter (one
decimeter The decimetre (SI symbol dm) or decimeter ( American spelling) is a unit Unit may refer to: Arts and entertainment * UNIT, a fictional military organization in the science fiction television series ''Doctor Who'' * Unit of action, a discrete p ...
). Radio waves with frequencies above the UHF band fall into the
super-high frequency Super high frequency (SHF) is the ITU designation for radio frequencies (RF) in the range between 3 and 30 gigahertz The hertz (symbol: Hz) is the SI derived unit, derived unit of frequency in the International System of Units (SI) an ...
(SHF) or
microwave Microwave is a form of electromagnetic radiation In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science that studies mat ...

microwave
frequency range. Lower frequency signals fall into the VHF (
very high frequency Very high frequency (VHF) is the International Telecommunication Union, ITU designation for the range of radio frequency electromagnetic waves (radio waves) from 30 to 300 megahertz (MHz), with corresponding wavelengths of ten meters to one mete ...
) or lower bands. UHF radio waves propagate mainly by
line of sight Line of sight (adjectival form line-of-sight) may refer to: Common meanings * Sightline, an unobstructed line-of-sight between a subject and object * Line of sight (gaming), visibility on a gaming field, ''i.e.'' who can see what Arts and enterta ...
; they are blocked by hills and large buildings although the transmission through building walls is strong enough for indoor reception. They are used for
television broadcasting A television network or broadcaster is a telecommunications network for distribution of television program content, where a central operation provides programming to many television stations or pay television providers. Until the mid-1980s, te ...
,
cell phones A mobile phone, cellular phone, cell phone, cellphone, handphone, or hand phone, sometimes shortened to simply mobile, cell or just phone, is a portable telephone that can make and receive telephone call, calls over a radio frequency link wh ...

cell phones
, satellite communication including
GPS The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government The federal government of the United States (U.S. federal government) is the national ...

GPS
,
personal radio service A personal radio service is any system that allows individual to operate radio transmitters and receivers for personal purposes with minimal or no special license or individual authorization. Personal radio services exist around the world and typica ...
s including Wi-Fi and Bluetooth, walkie-talkies, cordless phones, and numerous other applications. The Institute of Electrical and Electronics Engineers, IEEE defines the UHF Radio spectrum#IEEE, radar band as frequencies between 300 MHz and 1 GHz. Two other IEEE radar bands overlap the ITU UHF band: the L band between 1 and 2 GHz and the S band between 2 and 4 GHz.


Propagation characteristics

Radio waves in the UHF band travel almost entirely by line-of-sight propagation (LOS) and ground reflection; unlike in the High frequency, HF band there is little to no reflection from the ionosphere (skywave propagation), or ground wave. UHF radio waves are blocked by hills and cannot travel beyond the horizon, but can penetrate foliage and buildings for indoor reception. Since the wavelengths of UHF waves are comparable to the size of buildings, trees, vehicles and other common objects, reflection and Knife-edge effect, diffraction from these objects can cause fading due to multipath propagation, especially in built-up urban areas. Atmospheric moisture reduces, or Attenuation, attenuates, the strength of UHF signals over long distances, and the attenuation increases with frequency. UHF TV signals are generally more degraded by moisture than lower bands, such as Very high frequency, VHF TV signals. Since UHF transmission is limited by the visual horizon to 30–40 miles (48–64 km) and usually to shorter distances by local terrain, it allows the same frequency channels to be reused by other users in neighboring geographic areas (frequency reuse). Radio repeaters are used to retransmit UHF signals when a distance greater than the line of sight is required. Occasionally when conditions are right, UHF radio waves can travel long distances by tropospheric ducting as the atmosphere warms and cools throughout the day.


Antennas

The length of an antenna (radio), antenna is related to the length of the radio waves used. Due to the short wavelengths, UHF antennas are conveniently stubby and short; at UHF frequencies a monopole antenna, quarter-wave monopole, the most common omnidirectional antenna is between 2.5 and 25 cm long. UHF wavelengths are short enough that efficient transmitting antennas are small enough to mount on handheld and mobile devices, so these frequencies are used for two-way radio, two-way land mobile radio systems, such as walkie-talkies, two way radios in vehicles, and for portable wireless devices; cordless phones and cell phones. Omnidirectional UHF antennas used on mobile devices are usually short whip antenna, whips, sleeve dipole antenna, dipoles, rubber ducky antennas or the planar inverted F antenna (PIFA) used in cellphones. Higher gain omnidirectional UHF antennas can be made of collinear antenna array, collinear arrays of dipole antenna, dipoles and are used for mobile base stations and sector antenna, cellular base station antennas. The short wavelengths also allow directional antenna, high gain antennas to be conveniently small. High gain antennas for point-to-point (telecommunications), point-to-point communication links and UHF television reception are usually Yagi-Uda antenna, Yagi, log periodic antenna, log periodic, corner reflector antenna, corner reflectors, or reflective array antennas. At the top end of the band, slot antennas and parabolic antenna, parabolic dishes become practical. For satellite communication, helical antenna, helical, and turnstile antennas are used since satellites typically employ circular polarization which is not sensitive to the relative orientation of the transmitting and receiving antennas. For television broadcasting specialized vertical radiators that are mostly modifications of the slot antenna or reflective array antenna are used: the slotted cylinder, zig-zag, and panel antennas.


Applications

UHF television broadcasting fulfilled the demand for additional over-the-air television channels in urban areas. Today, much of the bandwidth has been reallocated to land mobile, land mobile radio system, Terrestrial Trunked Radio, trunked radio and mobile telephone use. UHF channels are still used for digital television. Since at UHF frequencies transmitting antennas are small enough to install on portable devices, the UHF spectrum is used worldwide for land mobile radio systems, two-way radios used for voice communication for commercial, industrial, public safety, and military purposes. Examples of personal radio services are General Mobile Radio Service, GMRS, PMR446, and UHF CB. Some wireless computer networks use UHF frequencies. The widely adopted GSM and UMTS cellular networks use UHF cellular frequencies. Major telecommunications providers have deployed voice and data cellular networks in VHF/UHF range. This allows mobile phones and mobile computing devices to be connected to the public switched telephone network and the Internet. UHF radars are said to be effective at tracking stealth fighters, if not stealth bombers. Wi-Fi operates at 2412 MHz-2484 MHz. LTE also operates on UHF frequencies


Examples of UHF frequency allocations


Australia

* UHF CB, UHF citizens band (Land mobile service): 476–477 MHz * Television broadcasting uses Australian and New Zealand television frequencies, UHF channels between 503 and 694 MHz * Fixed point-to-point Link 450.4875 - 451.5125 MHz * Land mobile service 457.50625 - 459.9875 MHz * Mobile satellite service: 406.0000 - 406.1000 MHz * Segment and Service examples: Land mobile for private, Australian, State and Territory Government, Rail industry and Mobile-Satellite


Canada

* 430–450 MHz: Amateur radio (70 cm band) * 470–806 MHz: Terrestrial television (with select channels in the 600 & 700 MHz bands left vacant) * 1452–1492 MHz: Digital Audio Broadcasting (L band) * Many other frequency assignments for Canada and Mexico are similar to their US counterparts


United Kingdom

*380–399.9 MHz: Terrestrial Trunked Radio (TETRA) service for emergency use *430–440 MHz: Amateur radio (70-centimeter band, 70 cm band) *446.0–446.2 MHz : European unlicensed PMR service => PMR446 *457–464 MHz: Scanning telemetry and telecontrol, assigned mostly to the water, gas, and electricity industries *606–614 MHz: Radio microphones and radio-astronomy *470–862 MHz: Previously used for Analogue terrestrial television in the United Kingdom#625 line system, analogue TV channels 21–69 (until 2012). **Currently channels 21–37, 39–48, plus 55 and 56, are used for Freeview (UK), Freeview digital TV. Channel 38 was used for radio astronomy but has been cleared to allow Programme making and special events, PMSE users access on a licensed, shared basis. **694-790 MHz: i.e. Channels 49-60 are in the process of being cleared, to allow these channels to be allocated for 5G cellular communication, however, Channels 55 and 56 are being used for COM 7 and COM 8 multiplexes for HD services. **791–862 MHz, i.e. channels 61–69 inclusive were previously used for licensed and shared wireless microphones (channel 69 only), has since been allocated to 4G cellular communications. *863–865 MHz: Used for licence-exempt wireless systems. *863–870 MHz: Short Range Devices, Short range devices, LPWAN Internet of things, IoT devices such as NarrowBand IOT, NarrowBand-IoT. *870–960 MHz: Cellular communications (GSM900 - Vodafone and O2 only) including GSM-R and future TETRA *1240–1325 MHz: Amateur radio (23-centimeter band, 23 cm band) *1710–1880 MHz: 2G Cellular communications (GSM1800) *1880–1900 MHz: Digital Enhanced Cordless Telecommunications, DECT cordless telephone *1900–1980 MHz: 3G cellular communications - mobile phone uplink *2110–2170 MHz: 3G cellular communications - base station downlink *2310–2450 MHz: Amateur radio (13-centimeter band, 13 cm band)


United States

UHF channels are used for digital television transition in the United States, digital television broadcasting on both North American broadcast television frequencies, over the air channels and North American cable television frequencies, cable television channels. Since 1962, UHF channel tuners (at the time, channels 14-83) have been required in television receivers by the All-Channel Receiver Act. However, because of their more limited range, and because few sets could receive them until older sets were replaced, UHF channels were less desirable to broadcasters than VHF channels (and licenses sold for lower prices). A complete list of US Television Frequency allocations can be found at North American television frequencies, North American Television Frequencies. There is a considerable amount of lawful unlicensed activity (cordless phones, wireless networking) clustered around 900 MHz and 2.4 GHz, regulated under Title 47 CFR Part 15. These ISM bands – frequencies with a higher unlicensed power permitted for use originally by Industrial, Scientific, Medical apparatus – are now some of the most crowded in the spectrum because they are open to everyone. The 2.45 GHz frequency is the standard for use by microwave ovens, adjacent to the frequencies allocated for Bluetooth network devices. The spectrum from 806 MHz to 890 MHz (UHF channels 70–83) was taken away from TV broadcast services in 1983, primarily for advanced Mobile Phone System, analog mobile telephony. In 2009, as part of the Digital television#Switch-off time announced, transition from analog to digital over-the-air broadcast of television, the spectrum from 698 MHz to 806 MHz (UHF channels 52–69) was removed from TV broadcasting, making it available for other uses. Channel 55, for instance, was sold to Qualcomm for their MediaFLO service, which was later sold to AT&T, and discontinued in 2011. Some US broadcasters had been offered incentives to vacate this channel early, permitting its immediate mobile use. The Federal Communications Commission, FCC's scheduled United States 2008 wireless spectrum auction, auction for this newly available spectrum was completed in March 2008. The FCC has allowed Americans to connect any device and any application to the 22 MHz of radio spectrum that people are calling the 700 MHz band. The FCC did not include a wholesale condition, which would have required the owner of the band to resell bandwidth to third parties who could then service the end user. Google argued that the wholesale requirement would have stimulated internet competition. As of 2007, 96% of the country's broadband access was controlled by DSL and cable providers. A wholesale condition could have meant a third option for internet service. *225–420 MHz: Government use, including meteorology, military aviation, and federal two-way use *420–450 MHz: Government radiolocation, amateur radio satellite and amateur radio (70-centimeter band, 70 cm band), MedRadio *450–470 MHz: UHF business band, General Mobile Radio Service, and Family Radio Service 2-way "walkie-talkies", public safety *470–512 MHz: Low-band TV channels 14–20 (shared with public safety land mobile 2-way radio in 12 major metropolitan areas scheduled to relocate to 700 MHz band by 2023) *512–608 MHz: Medium-band TV channels 21–36 *608–614 MHz: Channel 37 used for radio astronomy and wireless medical telemetry *614–698 MHz: Mobile broadband shared with TV channels 38–51 2008 United States wireless spectrum auction, auctioned in April 2017. TV stations will relocate by 2020. **617–652 MHz: Mobile broadband service downlink **652–663 MHz: Wireless microphones (higher priority) and unlicensed devices (lower priority) **663–698 MHz: Mobile broadband service uplink *698–806 MHz: United States 2008 wireless spectrum auction, Was auctioned in March 2008; bidders got full use after the transition to Digital television, digital TV was completed on June 12, 2009 (formerly high-band UHF TV channels 52–69) *806–816 MHz: Public safety and commercial 2-way (formerly TV channels 70–72) *817–824 MHz: ESMR band for wideband mobile services (mobile phone) (formerly public safety and commercial 2-way) *824–849 MHz: Cellular A & B franchises, terminal (mobile phone) (formerly TV channels 73–77) *849–851 MHz: Commercial aviation air-ground systems (Gogo Inflight Internet, Gogo) *851–861 MHz: Public safety and commercial 2-way (formerly TV channels 77–80) *862–869 MHz: ESMR band for wideband mobile services (base station) (formerly public safety and commercial 2-way) *869–894 MHz: Cellular A & B franchises, base station (formerly TV channels 80–83) *894–896 MHz: Commercial aviation air-ground systems (Gogo Inflight Internet, Gogo) *896–901 MHz: Commercial 2-way radio *901–902 MHz: Narrowband PCS: commercial narrowband mobile services *902–928 MHz: ISM band, amateur radio (33-centimeter band, 33 cm band), cordless phones and stereo, radio-frequency identification, datalinks *928–929 MHz: SCADA, alarm monitoring, meter reading systems and other narrowband services for a company internal use *929–930 MHz: Pagers *930–931 MHz: Narrowband PCS: commercial narrowband mobile services *931–932 MHz: Pagers *932–935 MHz: Fixed microwave services: distribution of video, audio and other data *935–940 MHz: Commercial 2-way radio *940–941 MHz: Narrowband PCS: commercial narrowband mobile services *941–960 MHz: Mixed studio-transmitter fixed links, SCADA, other. *960–1215 MHz: Aeronautical radionavigation *1240–1300 MHz: Amateur radio (23-centimeter band, 23 cm band) *1300–1350 MHz: Long range radar systems *1350–1390 MHz: Military air traffic control and mobile telemetry systems at test ranges *1390–1395 MHz: Proposed wireless medical telemetry service. TerreStar Corporation, TerreStar failed to provide service by the required deadline. *1395–1400 MHz: Wireless medical telemetry service *1400–1427 MHz: Earth exploration, radio astronomy, and space research *1427–1432 MHz: Wireless medical telemetry service *1432–1435 MHz: Proposed wireless medical telemetry service. TerreStar Corporation, TerreStar failed to provide service by the required deadline. *1435–1525 MHz: Military use mostly for aeronautical mobile telemetry (therefore not available for Digital Audio Broadcasting, unlike Canada/Europe) *1525–1559 MHz: SkyTerra, Skyterra downlink (Ligado Networks, Ligado is seeking FCC permission for terrestrial use) **1526–1536 MHz: proposed Ligado downlink **1536–1559 MHz: proposed guard band *1559–1610 MHz: Radionavigation-satellite service, Radio Navigation Satellite Services (RNSS) Upper L-band **1563–1587 MHz: Global Positioning System, GPS L1 band **1593–1610 MHz: GLONASS G1 band **1559–1591 MHz: Galileo (satellite navigation), Galileo E1 band (overlapping with GPS L1) *1610–1660.5 MHz: Mobile Satellite Service **1610–1618: Globalstar uplink **1618–1626.5 MHz: Iridium satellite constellation, Iridium uplink and downlink **1626.5–1660.5 MHz: SkyTerra, Skyterra uplink (Ligado Networks, Ligado is seeking FCC permission for terrestrial use) ***1627.5–1637.5 MHz: proposed Ligado uplink 1 ***1646.5–1656.5 MHz: proposed Ligado uplink 2 *1660.5–1668.4 MHz: Radio astronomy observations. Transmitting is not permitted. *1668.4–1670 MHz: Radio astronomy observations. Weather balloons may utilize the spectrum after an advance notice. *1670–1675 MHz: Geostationary Operational Environmental Satellite transmissions to three earth stations in Wallops Island, VA; Greenbelt, MD and Fairbanks, AK. Nationwide broadband service license in this range is held by a subsidiary of Crown Castle International Corp. who is trying to provide service in cooperation with Ligado Networks. *1675–1695 MHz: Meteorological federal users *1695–1780 MHz: Advanced Wireless Services, AWS mobile phone uplink (UL) operating band **1695–1755 MHz: AWS-3 blocks A1 and B1 **1710–1755 MHz: AWS-1 blocks A, B, C, D, E, F **1755–1780 MHz: AWS-3 blocks G, H, I, J (various federal agencies transitioning by 2025) *1780–1850 MHz: exclusive federal use (Air Force satellite communications, Army's cellular-like communication system, other agencies) *1850–1920 MHz: PCS mobile phone—order is A, D, B, E, F, C, G, H blocks. A, B, C = 15 MHz; D, E, F, G, H = 5 MHz *1920–1930 MHz: Digital Enhanced Cordless Telecommunications, DECT cordless telephone *1930–2000 MHz: PCS base stations—order is A, D, B, E, F, C, G, H blocks. A, B, C = 15 MHz; D, E, F, G, H = 5 MHz *2000–2020 MHz: lower AWS-4 downlink (mobile broadband) *2020–2110 MHz: Cable Antenna Relay service, Local Television Transmission service, TV Broadcast Auxiliary service, Earth Exploration Satellite service *2110–2200 MHz: Advanced Wireless Services, AWS mobile broadband downlink **2110–2155 MHz: AWS-1 blocks A, B, C, D, E, F **2155–2180 MHz: AWS-3 blocks G, H, I, J **2180–2200 MHz: upper AWS-4 *2200–2290 MHz: NASA satellite tracking, telemetry and control (space-to-Earth, space-to-space) *2290–2300 MHz: NASA Deep Space Network *2300–2305 MHz: Amateur radio (13-centimeter band, 13 cm band, lower segment) *2305–2315 MHz: WCS mobile broadband service uplink blocks A and B *2315–2320 MHz: WCS block C (AT&T is pursuing smart grid deployment) *2320–2345 MHz: Satellite radio (Sirius XM) *2345–2350 MHz: WCS block D (AT&T is pursuing smart grid deployment) *2350–2360 MHz: WCS mobile broadband service downlink blocks A and B *2360–2390 MHz: Aircraft landing and safety systems *2390–2395 MHz: Aircraft landing and safety systems (secondary deployment in a dozen of airports), amateur radio otherwise *2395–2400 MHz: Amateur radio (13-centimeter band, 13 cm band, upper segment) *2400–2483.5 MHz: ISM band, ISM, IEEE 802.11, 802.11b, 802.11g, 802.11n wireless LAN, IEEE 802.15.4-2006, Bluetooth, radio-controlled aircraft (strictly for spread spectrum use), microwave ovens, Zigbee *2483.5–2495 MHz: Globalstar downlink and Terrestrial Low Power Service suitable for TD-LTE small cells *2495–2690 MHz: Educational Broadcast and Broadband Radio Services *2690–2700 MHz: Receive-only range for radio astronomy and space research


See also

*Digital Audio Broadcasting and its regional implementations of DAB, regional implementations *Digital terrestrial television *The Thing (listening device)


References


External links


U.S. cable television channel frequencies
*Tomislav Stimac, "

'". IK1QFK Home Page (vlf.it). {{Authority control Radio spectrum Television technology Wireless