ULTRA HIGH FREQUENCY (UHF) is the
The IEEE defines the UHF radar band as frequencies between 300 MHz
and 1 GHz. Two other IEEE radar bands overlap the
* 1 Propagation characteristics * 2 Antennas * 3 Applications
* 4 Examples of UHF frequency allocations
* 4.1 Australia * 4.2 Canada * 4.3 United Kingdom * 4.4 United States
* 5 See also * 6 References * 7 External links
Walkie talkies which operate on the 446 MHz PMR (Professional
Since UHF transmission is limited by the visual horizon to 30–40
miles (48–64 km) and often to shorter distances by local terrain, it
allows the same frequency channels to be reused by other users in
neighboring geographic areas (frequency reuse ). Public safety,
business communications and personal radio services such as GMRS ,
PMR446 , and
UHF CB are often found on UHF frequencies as well as IEEE
802.11 wireless LANs ("Wi-Fi"). The widely adopted
Occasionally when conditions are right, UHF radio waves can travel long distances by tropospheric ducting as the atmosphere warms and cools throughout the day.
Corner reflector UHF-TV antenna from 1950s
The length of an antenna is related to the length of the radio waves used. The UHF antenna is stubby and short; at UHF frequencies a 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 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 whips , sleeve dipoles , rubber ducky antennas or the planar inverted F antenna (PIFA) used in cellphones. Higher gain omnidirectional UHF antennas can be made of collinear arrays of dipoles and are used for mobile base stations and cellular base station antennas .
The short wavelengths also allow high gain antennas to be conveniently small. High gain antennas for point-to-point communication links and UHF television reception are usually Yagi , log periodic , corner reflectors , or reflective array antennas . At the top end of the band slot antennas and parabolic dishes become practical. For satellite communication, 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 helical antenna are used: the slotted cylinder, zig-zag, and panel antennas.
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, trunked radio and mobile telephone use. UHF channels are still used for digital television .
UHF spectrum is used worldwide for land mobile radio systems for commercial, industrial, public safety, and military purposes. Many personal radio services use frequencies allocated in the UHF band, although exact frequencies in use differ significantly between countries.
Major telecommunications providers have deployed voice and data
cellular networks in UHF/
UHF radars are said to be effective at tracking stealth fighters, if not stealth bombers.
EXAMPLES OF UHF FREQUENCY ALLOCATIONS
* UHF Citizens Band : 476–477 MHz * Television broadcasting uses UHF channels between 503 and 694 MHz
* 430–450 MHz: Amateur radio (ham – 70 cm band) * 470–806 MHz: Terrestrial television (with select channels in the 700 MHz band left vacant) * 1452–1492 MHz: Digital Audio Broadcasting ( L band ) * Many other frequency assignments for Canada and Mexico are similar to their US counterparts
* 380–399.9 MHz:
Terrestrial Trunked Radio
* 470–862 MHz: Previously used for analogue TV channels 21–69 (until 2012).
* Currently channels 21–35, 37 and 39–60 are used for Freeview digital TV. Channel 36 is used for radar; channel 38 was used for radio astronomy but has been cleared to allow PMSE users access on a licensed, shared basis. * 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 , LPWAN IoT devices such as NarrowBand-IoT . * 870–960 MHz: Cellular communications (GSM900 - Vodafone and O2 only) including GSM-R and future TETRA * 1240–1325 MHz: Amateur radio (ham – 23 cm band ) * 1710–1880 MHz: 2G Cellular communications (GSM1800) * 1880–1900 MHz: 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 (ham – 13 cm band )
UHF channels are used for digital television broadcasting on both
over the air channels and 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
A complete list of US Television
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
The spectrum from 806 MHz to 890 MHz (UHF channels 70–83) was taken away from TV broadcast services in 1983, primarily for analog mobile telephony .
In 2009, as part of the 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 is resold under various mobile telephone network brands. Some US broadcasters had been offered incentives to vacate this channel early, permitting its immediate mobile use. The FCC 's scheduled auction for this newly available spectrum was completed in March 2008.
* 225–420 MHz: Government use, including meteorology , military aviation, and federal two-way use
* 420–450 MHz: Government radiolocation and amateur radio (70 cm band )
* 433 MHz: Short range consumer devices including automotive, alarm systems, home automation, temperature sensors
* 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 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: Was auctioned in March 2008; bidders got full use after the transition to 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 ) * 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 D, E, F, G, H = 5 MHz * 1920–1930 MHz: 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
* 2110–2155 MHz: 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
* 2290–2300 MHz: NASA Deep Space Network * 2300–2305 MHz: Amateur radio (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 and XM ) * 2345–2350 MHz: WCS block D (AT">
* ^ IEEE Std 521-2002 _Standard Letter Designations for
* U.S. cable television channel frequencies * Tomislav Stimac, "_Definition of frequency bands (VLF, ELF... etc.)_". IK1QFK Home