Very high frequency

Very high frequency (VHF) is the ITU designation[1] for the range of radio frequency electromagnetic waves (radio waves) from 30 to 300 megahertz (MHz), with corresponding wavelengths of ten meters to one meter. Frequencies immediately below VHF are denoted high frequency (HF), and the next higher frequencies are known as ultra high frequency (UHF).

Common uses for radio waves in the VHF band are digital audio broadcasting (DAB) and FM radio broadcasting, television broadcasting, two-way land mobile radio systems (emergency, business, private use and military), long range data communication up to several tens of kilometers with radio modems, amateur radio, and marine communications. Air traffic control communications and air navigation systems (e.g. VOR & ILS) work at distances of 100 kilometres (62 mi) or more to aircraft at cruising altitude.

In the Americas and many other parts of the world, VHF Band I was used for the transmission of analog television. As part of the worldwide transition to digital terrestrial television most countries require broadcasters to air television in the VHF range using digital rather than analog format.

Propagation characteristics

Radio waves in the VHF band propagate mainly by line-of-sight and ground-bounce paths; unlike in the HF band there is only some reflection at lower frequencies from the ionosphere (skywave propagation).[2] They do not follow the contour of the Earth as ground waves and so are blocked by hills and mountains, although because they are weakly refracted (bent) by the atmosphere they can travel somewhat beyond the visual horizon out to about 160 km (100 miles). They can penetrate building walls and be received indoors, although in urban areas reflections from buildings cause multipath propagation, which can interfere with television reception. Atmospheric radio noise and interference (RFI) from electrical equipment is less of a problem in this and higher frequency bands than at lower frequencies. The VHF band is the first band at which efficient transmitting antennas are small enough that they can be mounted on vehicles and portable devices, so the band is used for two-way land mobile radio systems, such as walkie-talkies, and two way radio communication with aircraft (Airband) and ships (marine radio). Occasionally, when conditions are right, VHF waves can travel long distances by tropospheric ducting due to refraction by temperature gradients in the atmosphere.
Line-of-sight calculation
"Rabbit-ears" VHF television antenna (the small loop is a separate UHF antenna).

For analog TV, VHF transmission range is a function of transmitter power, receiver sensitivity, and distance to the horizon, since VHF signals propagate under normal conditions as a near line-of-sight phenomenon. The distance to the radio horizon is slightly extended over the geometric line of sight to the horizon, as radio waves are weakly bent back toward the Earth by the atmosphere.

An approximation to calculate the line-of-sight horizon distance (on Earth) is:

distance in nautical miles = \( 1.23\times\sqrt{ A_f} \) where \( A_f \) is the height of the antenna in feet
distance in kilometers = \( \sqrt{12.746 \times A_m} \) where \( A_{m} \) is the height of the antenna in meters.

These approximations are only valid for antennas at heights that are small compared to the radius of the Earth. They may not necessarily be accurate in mountainous areas, since the landscape may not be transparent enough for radio waves.

In engineered communications systems, more complex calculations are required to assess the probable coverage area of a proposed transmitter station.

The accuracy of these calculations for digital TV signals is being debated.[3]
Antennas
See also: UHF television broadcasting § UHF vs VHF
A VHF television broadcasting antenna. This is a common type called a super turnstile or batwing antenna.

VHF is the first band at which wavelengths are small enough that efficient transmitting antennas are short enough to mount on vehicles and handheld devices, a quarter wave whip antenna at VHF frequencies is 25 cm to 2.5 meter (10 inches to 8 feet) long. So the VHF and UHF wavelengths are used for two-way radios in vehicles, aircraft, and handheld transceivers and walkie-talkies. Portable radios usually use whips or rubber ducky antennas, while base stations usually use larger fiberglass whips or collinear arrays of vertical dipoles.

For directional antennas, the Yagi antenna is the most widely used as a high gain or "beam" antenna. For television reception, the Yagi is used, as well as the log-periodic antenna due to its wider bandwidth. Helical and turnstile antennas are used for satellite communication since they employ circular polarization. For even higher gain, multiple Yagis or helicals can be mounted together to make array antennas. Vertical collinear arrays of dipoles can be used to make high gain omnidirectional antennas, in which more of the antenna's power is radiated in horizontal directions. Television and FM broadcasting stations use collinear arrays of specialized dipole antennas such as batwing antennas.
Universal use

Certain subparts of the VHF band have the same use around the world. Some national uses are detailed below.

50–54 MHz: Amateur Radio 6-meter band.
108–118 MHz: Air navigation beacons VOR and Instrument Landing System localizer.
118–137 MHz: Airband for air traffic control, AM, 121.5 MHz is emergency frequency
144–146 MHz: Amateur Radio 2-meter band (Extends up to 148 MHz in some Regions).

By country
A plan showing VHF use in television, FM radio, amateur radio, marine radio and aviation.
Australia
See also: Australasian television frequencies

The VHF TV band in Australia was originally allocated channels 1 to 10-with channels 2, 7 and 9 assigned for the initial services in Sydney and Melbourne, and later the same channels were assigned in Brisbane, Adelaide and Perth. Other capital cities and regional areas used a combination of these and other frequencies as available. The initial commercial services in Hobart and Darwin were respectively allocated channels 6 and 8 rather than 7 or 9.

By the early 1960s it became apparent that the 10 VHF channels were insufficient to support the growth of television services. This was rectified by the addition of three additional frequencies-channels 0, 5A and 11. Older television sets using rotary dial tuners required adjustment to receive these new channels. Most TVs of that era were not equipped to receive these broadcasts, and so were modified at the owners' expense to be able to tune into these bands; otherwise the owner had to buy a new TV.

Several TV stations were allocated to VHF channels 3, 4 and 5, which were within the FM radio bands although not yet used for that purpose. A couple of notable examples were NBN-3 Newcastle, WIN-4 Wollongong and ABC Newcastle on channel 5. While some Channel 5 stations were moved to 5A in the 1970s and 80s, beginning in the 1990s, the Australian Broadcasting Authority began a process to move these stations to UHF bands to free up valuable VHF spectrum for its original purpose of FM radio. In addition, by 1985 the federal government decided new TV stations are to be broadcast on the UHF band.

Two new VHF, 9A and 12, have since been made available and are being used primarily for digital services (e.g. ABC in capital cities) but also for some new analogue services in regional areas. Because channel 9A is not used for television services in or near Sydney, Melbourne, Brisbane, Adelaide or Perth, digital radio in those cities are broadcast on DAB frequencies blocks 9A, 9B and 9C.

VHF radio is also used for marine Radio[4] as per its long-distance reachability comparing UHF frequencies.

Example allocation of VHF–UHF frequencies:[5]

Radionavigation 60: 84–86 MHz
Fixed Maritime Mobile: 130–135.7 MHz
Fixed Aeronautical radio navigation: 160–190 MHz
Broadcasting Aeronautical Radionavigation: 255–283.5 MHz
Aeronautical Radionavigation AUS 49 / Maritime Radionavigation (radiobeacons) 73: 315–325 MHz

New Zealand

44–51, 54–68 MHz: Band I Television (channels 1–3)
87.5–108 MHz: Band II Radio
174–230 MHz: Band III Television (channels 4–11)

Until 2013, the four main Free-to-Air TV stations in New Zealand used the VHF Television bands (Band I and Band III) to transmit to New Zealand households. Other stations, including a variety of pay and regional free-to-air stations, were forced to broadcast in the UHF band, since the VHF band had been very overloaded with four stations sharing a very small frequency band, which was so overcrowded that one or more channels would not be available in some smaller towns.

However, at the end of 2013, all television channels stopped broadcasting on the VHF bands, as New Zealand moved to digital television broadcasting, requiring all stations to either broadcast on UHF or satellite (where UHF was unavailable) utilising the Freeview service.[6]

Refer to Australasian television frequencies for more information.

United Kingdom

British television originally used VHF band I and band III. Television on VHF was in black and white with 405-line format (although there were experiments with all three colour systems-NTSC, PAL, and SECAM-adapted for the 405-line system in the late 1950s and early 60s).

British colour television was broadcast on UHF (channels 21-69), beginning in the late 1960s. From then on, TV was broadcast on both VHF and UHF (VHF being a monochromatic downconversion from the 625-line colour signal), with the exception of BBC2 (which had always broadcast solely on UHF). The last British VHF TV transmitters closed down on January 3, 1985. VHF band III is now used in the UK for digital audio broadcasting, and VHF band II is used for FM radio, as it is in most of the world.

Unusually, the UK has an amateur radio allocation at 4 metres, 70-70.5 MHz.
United States and Canada

Frequency assignments between US and Canadian users are closely coordinated since much of the Canadian population is within VHF radio range of the US border. Certain discrete frequencies are reserved for radio astronomy. The general services in the VHF band are:

30–49.6 MHz: Licensed 2-way land mobile communication, with various sub-bands.[a]
30–88 MHz: Military VHF FM, including SINCGARS
43–50 MHz: Cordless telephones, 49 MHz FM walkie-talkies and radio controlled toys, and mixed 2-way mobile communication. The FM broadcast band originally operated here (42–50 MHz) before it was moved to 88–108 MHz.
50–54 MHz: Amateur radio 6 meter band
50.800–51 MHz: Radio-controlled aircraft (on ten fixed frequencies at 20 kHz spacing) with an FCC Amateur Radio Service license, flown under FCC Part 97, rule 97.215.[7]
54–72 and 76–88 MHz TV channels 2–6 (VHF-Lo), known as "Band I" internationally; some DTV stations will appear here. See North American broadcast television frequencies
72–76 MHz: Radio controlled models, industrial remote control, and other devices. Model aircraft operate on 72 MHz while surface models operate on 75 MHz in the US and Canada, air navigation beacons 74.8–75.2 MHz.
87.5–108 MHz: FM radio broadcasting (87.9–91.9 non-commercial, 92–108 commercial in the United States) (known as "Band II" internationally)
108–118 MHz: Air navigation beacons VOR
118–137 MHz: Airband for air traffic control, AM, 121.5 MHz is an emergency frequency
137–138 MHz Space research, space operations, meteorological satellite[8]
138–144 MHz: Land mobile, auxiliary civil services, satellite, space research, and other miscellaneous services
144–148 MHz: Amateur radio 2-meter band
148–150 MHz: Land mobile, fixed, satellite
150–156 MHz: "VHF business band," public safety, the unlicensed Multi-Use Radio Service (MURS), and other 2-way land mobile, FM
156–158 MHz VHF Marine Radio; 156.8 MHz (Channel 16) is the maritime emergency and contact frequency.
159.81-161.565 MHz railways [b] 159.81–160.2 are railroads in Canada only and is used by trucking companies in the U.S.
160.6–162 Wireless microphones and TV/FM broadcast remote pickup
162.4–162.55: NOAA Weather Stations, narrowband FM, Weatheradio Canada Stations
174–216 MHz television channels 7–13 (VHF-Hi), known as "Band III" internationally. A number of DTV channels have begun broadcasting here, especially many of the stations which were assigned to these channels for previous analog operation.
174–216 MHz: professional wireless microphones (low power, certain exact frequencies only)
216–222 MHz: land mobile, fixed, maritime mobile,[8]
222–225 MHz: 1.25 meters (US) (Canada 219–220, 222–225 MHz) amateur radio
225 MHz and above (UHF): Military aircraft radio, 243 MHz is an emergency frequency (225–400 MHz) AM, including HAVE QUICK, dGPS RTCM-104

Cable television, though not transmitted aerially, uses a spectrum of frequencies overlapping VHF.[9]
VHF television

The U.S. FCC allocated television broadcasting to a channelized roster as early as 1938 with 19 channels. That changed three more times: in 1940 when Channel 19 was deleted and several channels changed frequencies, then in 1946 with television going from 18 channels to 13 channels, again with different frequencies, and finally in 1948 with the removal of Channel 1 (analog channels 2-13 remain as they were, even on cable television).[10]
87.5–87.9 MHz

87.5–87.9 MHz is a radio frequency which, in most of the world, is used for FM broadcasting. In North America, however, this bandwidth is allocated to VHF television channel 6 (82–88 MHz). The analog audio for TV channel 6 is broadcast at 87.75 MHz (adjustable down to 87.74). Several stations, most notably those joining the Pulse 87 franchise, have operated on this frequency as radio stations, though they use television licenses. As a result, FM radio receivers such as those found in automobiles which are designed to tune into this frequency range could receive the audio for analog-mode programming on the local TV channel 6 while in North America.

The FM broadcast channel at 87.9 MHz is normally off-limits for FM audio broadcasting; it is reserved for displaced class D stations which have no other frequencies in the normal 88.1–107.9 MHz subband to move to. So far, only two stations have qualified to operate on 87.9 MHz: 10–watt KSFH in Mountain View, California and 34–watt translator K200AA in Sun Valley, Nevada.
Unlicensed operation

In some countries, particularly the United States and Canada, limited low-power license-free operation is available in the FM broadcast band for purposes such as micro-broadcasting and sending output from CD or digital media players to radios without auxiliary-in jacks, though this is illegal in some other countries. This practice was legalised in the United Kingdom on 8 December 2006.[11]
See also

Marine VHF radio
TV radio
List of oldest radio stations
Apex (radio band)
FM broadcast band
Moving image formats
Polar mesosphere summer echoes
Television channel frequencies
Knife-edge effect
Instrument Landing System
VHF omnidirectional range
High frequency
Low frequency
Extremely low frequency
Ultra low frequency

Notes

The 42 MHz Segment is still in current use by the California Highway Patrol, New Jersey State Police, Tennessee Highway Patrol, and other state law enforcement agencies.

The 160 and 161 areas are Association of American Railroads (AAR) 99 channel railroad radios, issued to the railroad. For example, AAR 21 is 160.425 MHz and that is issued to Tennessee Valley Railroad Museum, as well as other railroads that want AAR Channel 21.

References

"Rec. ITU-R V.431-7, Nomenclature of the frequency and wavelength bands used in telecommunications" (PDF). ITU. Archived from the original (PDF) on 31 October 2013. Retrieved 20 February 2013.
Seybold, John S. (2005). Introduction to RF Propagation. John Wiley and Sons. pp. 9–10. ISBN 978-0471743682.
Grotticelli, Michael (2009-06-22). "DTV Transition Not So Smooth in Some Markets". Broadcast Engineering. Archived from the original on June 28, 2009. Retrieved 2009-06-24.
"Marine VHF radio". ACMA.
"Australian radiofrequency spectrum plan". Planning. ACMA.
"Going Digital - When is my area going digital?". goingdigital.co.nz. Ministry for Culture and Heritage. Archived from the original on 17 October 2011. Retrieved 20 October 2011.
[1]
Canadian Table of Frequency Allocations 9 kHz – 275 GHz (2005 (revised February 2007) ed.). Industry Canada. February 2007. pp. 29–30.
"Cable TV Channel Frequencies". www.jneuhaus.com. Archived from the original on 23 August 2017. Retrieved 27 April 2018.
"What Ever Happened to Channel 1?". tech-notes.tv. Tech Notes. Table 1. Archived from the original on 17 March 2017. Retrieved 27 April 2018.

"Change to the law to allow the use of low power FM transmitters for MP3 players". Ofcom. 23 November 2006. Archived from the original on 7 August 2011. Retrieved 2 October 2012.

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Broadcast bands with Roman numeral designations
VHF

Band I Band II Band III

UHF

Band IV Band V

SHF

Band VI

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Radio spectrum (ITU)

ELF
3 Hz/100 Mm
30 Hz/10 Mm

SLF
30 Hz/10 Mm
300 Hz/1 Mm

ULF
300 Hz/1 Mm
3 kHz/100 km

VLF
3 kHz/100 km
30 kHz/10 km

LF
30 kHz/10 km
300 kHz/1 km

MF
300 kHz/1 km
3 MHz/100 m

HF
3 MHz/100 m
30 MHz/10 m

VHF
30 MHz/10 m
300 MHz/1 m

UHF
300 MHz/1 m
3 GHz/100 mm

SHF
3 GHz/100 mm
30 GHz/10 mm

EHF
30 GHz/10 mm
300 GHz/1 mm

THF
300 GHz/1 mm
3 THz/0.1 mm

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Electromagnetic spectrum

Gamma rays X-rays Ultraviolet Visible Infrared Microwave Radio
Frequency vs. wave length.svg
← higher frequencies longer wavelengths →

X-rays

soft X-ray hard X-ray

Ultraviolet

Extreme ultraviolet Vacuum ultraviolet Lyman-alpha FUV MUV NUV UVC UVB UVA

Visible (optical)

Violet Blue Cyan Green Yellow Orange Red

Infrared

NIR SWIR MWIR LWIR FIR

Microwaves

W band V band Q band Ka band K band Ku band X band C band S band L band

Radio

THF EHF SHF UHF VHF HF MF LF VLF ULF SLF ELF

Wavelength types

Microwave Shortwave Medium wave Longwave

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Telecommunications
History

Beacon Broadcasting Cable protection system Cable TV Communications satellite Computer network Data compression
audio DCT image video Digital media
Internet video online video platform social media streaming Drums Edholm's law Electrical telegraph Fax Heliographs Hydraulic telegraph Information Age Information revolution Internet Mass media Mobile phone
Smartphone Optical telecommunication Optical telegraphy Pager Photophone Prepaid mobile phone Radio Radiotelephone Satellite communications Semaphore Semiconductor
device MOSFET transistor Smoke signals Telecommunications history Telautograph Telegraphy Teleprinter (teletype) Telephone The Telephone Cases Television
digital streaming Undersea telegraph line Videotelephony Whistled language Wireless revolution

Telecom-icon.svg
Pioneers

Nasir Ahmed Edwin Howard Armstrong Mohamed M. Atalla John Logie Baird Paul Baran John Bardeen Alexander Graham Bell Tim Berners-Lee Jagadish Chandra Bose Walter Houser Brattain Vint Cerf Claude Chappe Yogen Dalal Donald Davies Lee de Forest Philo Farnsworth Reginald Fessenden Elisha Gray Oliver Heaviside Erna Schneider Hoover Harold Hopkins Internet pioneers Bob Kahn Dawon Kahng Charles K. Kao Narinder Singh Kapany Hedy Lamarr Innocenzo Manzetti Guglielmo Marconi Robert Metcalfe Antonio Meucci Jun-ichi Nishizawa Radia Perlman Alexander Stepanovich Popov Johann Philipp Reis Claude Shannon Henry Sutton Nikola Tesla Camille Tissot Alfred Vail Charles Wheatstone Vladimir K. Zworykin

Transmission
media

Coaxial cable Fiber-optic communication
optical fiber Free-space optical communication Molecular communication Radio waves
wireless Transmission line
data transmission circuit telecommunication circuit

Network topology
and switching

Bandwidth Links Nodes
terminal Network switching
circuit packet Telephone exchange

Multiplexing

Space-division Frequency-division Time-division Polarization-division Orbital angular-momentum Code-division

Concepts

Communication protocols Computer network Data transmission Store and forward Telecommunications equipment

Types of network

Cellular network Ethernet ISDN LAN Mobile NGN Public Switched Telephone Radio Television Telex UUCP WAN Wireless network

Notable networks

ARPANET BITNET CYCLADES FidoNet Internet Internet2 JANET NPL network Usenet

Locations (by regions)

Africa Americas
North South Antarctica Asia Europe Oceania

Category Category List-Class article Outline Portal Portal Commons page Commons

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Analog television broadcasting topics
Systems

180-line 405-line (System A) 441-line 525-line (System J, System M) 625-line (System B, System C, System D, System G, System H, System I, System K, System L, System N) 819-line ( System E , System F )

Color systems

NTSC PAL PAL-M PAL-S PALplus SECAM

Video

Back porch and front porch Black level Blanking level Chrominance Chrominance subcarrier Colorburst Color killer Color TV Composite video Frame (video) Horizontal scan rate Horizontal blanking interval Luma Nominal analogue blanking Overscan Raster scan Safe area Television lines Vertical blanking interval White clipper

Sound

Multichannel television sound NICAM Sound-in-Syncs Zweikanalton

Modulation

Frequency modulation Quadrature amplitude modulation Vestigial sideband modulation (VSB)

Transmission

Amplifiers Antenna (radio) Broadcast transmitter/Transmitter station Cavity amplifier Differential gain Differential phase Diplexer Dipole antenna Dummy load Frequency mixer Intercarrier method Intermediate frequency Output power of an analog TV transmitter Pre-emphasis Residual carrier Split sound system Superheterodyne transmitter Television receive-only Direct-broadcast satellite television Television transmitter Terrestrial television Transposer Digital television transition

Frequencies & Bands

Frequency offset Microwave transmission Television channel frequencies UHF VHF

Propagation

Beam tilt Distortion Earth bulge Field strength in free space Noise (electronics) Null fill Path loss Radiation pattern Skew Television interference

Testing

Distortionmeter Field strength meter Vectorscope VIT signals Zero reference pulse

Artifacts

Dot crawl Ghosting Hanover bars Sparklies

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Analog and digital audio broadcasting
Terrestrial
Radio modulation

AM FM COFDM

Frequency allocations

LW (LF) MW (MF) SW (HF) VHF (low / mid / high) L band (UHF)

Digital systems

CAM-D DAB/DAB+ DRM/DRM+ FMeXtra HD Radio CDR DVB-T2 Lite

Satellite
Frequency allocations

C band Ku band L band S band

Digital systems

ADR DAB-S DVB-SH S-DMB SDR

Commercial radio providers

Sirius XM Sirius XM Canada

Codecs

AAC AMR-WB+ HDC HE-AAC MPEG-1 Audio Layer II

Subcarrier signals

AMSS DirectBand PAD RDS/RBDS SCA/SCMO DARC