Can you use a TV antenna for FM radio?
Partially guyed tower
Partially guyed towers can be used e.g. when a very high tower for FM and TV transmission is required, which should also carry antennas for directional radio services in a much lower height. In this cases the antennas for directional radio services are mounted on the top of the free-standing part of the tower, while the guyed mast on its top carry the FM and TV antennas.
They can be also used in order to upgrade small stable towers (like watertowers) with a long antenna mast for FM and TV broadcasting.
However their use is rare, and done only in some European countries.
Low-power broadcasting
LPFM stations are considered to be affordable compared to an average FM station, whose operating costs can run up to a million dollars, and could only afforded by businesses and the very wealthy. An antenna and transmitter can cost between $2,000 and $5,000.Unlike the former FM class D license, an LPFM station has no priority over broadcast translators in the allocation of available spectrum. This is problematic insofar as the regulations for broadcast translators exempts non-commercial stations from the requirement that translators be within the coverage area of the original station that they rebroadcast. However, this provision only affects translators in the non-commercial portion of the band. Stations in the commercial part of the spectrum must be fed over the air unless they are within the actual service area of the primary station. Since the translator window of 2003 was only open for commercial channels, the use of directly-fed via satellite FM translators, commonly called "Satellators", was never a factor in the 2003 window.
Radio
Aviation voice radios use Aircraft band VHF AM. AM is used so that multiple stations on the same channel can be received. (Use of FM would result in stronger stations blocking out reception of weaker stations due to FM's capture effect). Aircraft fly high enough that their transmitters can be received hundreds of miles away, even though they are using VHF.
Marine voice radios can use single sideband voice (SSB) in the shortwave High Frequency (HF—3 MHz to 30 MHz) radio spectrum for very long ranges or Marine VHF radio / "narrowband FM" in the VHF spectrum for much shorter ranges. Narrowband FM sacrifices fidelity to make more channels available within the radio spectrum, by using a smaller range of radio frequencies, usually with five kHz of deviation, versus the 75 kHz used by commercial FM broadcasts, and 25 kHz used for TV sound.
Ambient backscatter
Ambient backscatter uses existing radio frequency signals, such as radio, television and mobile telephony, to transmit data without a battery or power grid connection. Each such device uses an antenna to pick up an existing signal and convert it into tens to hundreds of microwatts of electricity. It uses that power to modify and reflect the signal with encoded data. Antennas on other devices, in turn, detect that signal and can respond accordingly.
Clansman (military radio)
A TURF (Tuning Unit Radio Frequency) is an Antenna Tuning Unit or ATU. It is used to artificially lengthen the antenna (or tune it) Often at HF wavelengths for example an antenna would be physically too long to attach to a radio without affecting portability and manoeuvrability. A shorter vehicle whip was more practicable and also field antennas were constructed with for example, vertical radiators constructed using the Racal 8 or 12 metre masts. Because these were an electrical compromise, they had to be tuned by use of a TURF (or electrically matched to the set). The TURF 25 Watt (a separate unit to the radio) is considered mandatory when using the VRC321: it tunes both unbalanced, end fed wires and whips and also balanced antennas such as the dipole.
WokFi
A significant advantage is that with a USB modem the RF signal is converted to a conventional digital signal at the antenna. Therefore, by using standard USB extension cables, the antenna can be located at a distance from the computer of five meters or more, with no concerns over microwave signal losses that would occur in an RF coaxial cable feedline of that length used to attach a conventional antenna to the RF input of a computer modem. Chaining active USB repeaters, it is possible to locate the antenna at much greater distances from the computer, which is especially useful when line-of-sight (LOS) obstacles (such as vegetation and walls) require the antenna to be located on a roof, for example. If using mesh reflectors, usually with a grid under 5 mm, the antenna will be lighter and present a smaller wind-load than larger dishes.
FM broadcast band
Second-hand automobiles imported from Japan contain a radio designed for the Japanese FM band, and importers often fit a "converter" to down-convert the 87.5 to 107.9 MHz band to the frequencies that the radio can accept. In addition to showing an incorrect frequency, there are two other disadvantages that can result in undesired performance; the converter cannot down-convert in full the regular international FM band (up to 20.5 MHz wide) to the only 14 MHz-wide Japanese band (unless the converter incorporates two user-switchable down-convert modes), and the car's antenna may perform poorly on the higher FM band. Some converters simply down-convert the FM band by 12 MHz, leading to logical frequencies (e.g. 78.9 for 90.9, 82.3 for 94.3, etc.), but leaving off the 102–108 MHz band. Also, RDS is not used in Japan, whereas most modern car radios available in Europe have this system. Also the converter may not allow pass-through of the MW band, which is used for AM broadcasting. A better solution is to replace the radio and antenna with ones designed for the country where the car will be used.
Australia had a similar situation with Australian TV channels 3, 4 and 5 that are between 88 and 108 MHz, and was intending to follow Japan, but in the end opted for the western bandplan, due to CCIR radios that entered the country. There were some radios sold in Australia for 76 to 90 MHz.
Antenna (radio)
At low frequencies (such as AM broadcast), arrays of vertical towers are used to achieve directionality and they will occupy large areas of land. For reception, a long Beverage antenna can have significant directivity. For non directional portable use, a short vertical antenna or small loop antenna works well, with the main design challenge being that of impedance matching. With a vertical antenna a "loading coil" at the base of the antenna may be employed to cancel the reactive component of impedance; small loop antennas are tuned with parallel capacitors for this purpose.
Effective radiated power
ERP for FM radio in the United States is always relative to a theoretical reference half-wave dipole antenna. (That is, when calculating ERP, the most direct approach is to work with antenna gain in dBd). To deal with antenna polarization, the Federal Communications Commission (FCC) lists ERP in both the horizontal and vertical measurements for FM and TV. Horizontal is the standard for both, but if the vertical ERP is larger it will be used instead.
Television antenna
In most countries, television broadcasting is allowed in the very high frequency (VHF) band from 47 to 68 MHz, called VHF low band or band I in Europe; 174 to 216 MHz, called VHF high band or band III in Europe, and in the ultra high frequency (UHF) band from 470 to 698 MHz, called band IV and V in Europe. The boundaries of each band vary somewhat in different countries.
Bell TV
Many types of remotes have been released over the years. Models 1000 and 2700 came out with very basic infrared (IR) remotes that could be used only to control the receivers themselves and would operate on all 16 remote addresses. Replacement remotes then came with universal functions allowing users to control the power and volume of their televisions along with VCRs and sound system receivers; these remotes can only operate on a single address at a time. Models equipped with a UHF antenna can respond to UHF remotes; these remotes use radio frequencies rather than IR signals to control the receivers. UHF signals can reach up to 30 meters, depending on the restrictions of building materials. All UHF-compatible receivers can simultaneously respond to IR signals except for model 4500. For this model, modification directions exist on the Internet to add IR receiving capability, in order for the receiver to respond to programmable universal remotes. Remote #2 of the 3200, 5200, 9200, and the remote for model 6100 are based on "UHF Pro". "UHF Pro" remotes are strictly compatible with the receivers they are provided with and do not function on regular UHF-compatible receivers. Additionally, "UHF Pro" remotes can only communicate with UHF frequencies and cannot control receivers via IR. To prevent interference with other UHF remotes in proximity, clients should change their remote addresses. All secondary remotes for dual tuners may also be converted to remote #1 by flipping the plastic bottom of the remote. This also switches its transmission mode from UHF Pro to regular UHF and IR, similar to how a 5900 remote operates.
Very low frequency
High power transmitting antennas for VLF frequencies are very large wire antennas, up to a mile across. They consist of a series of steel radio masts, linked at the top with a network of cables, often shaped like an umbrella or clotheslines. Either the towers themselves or vertical wires serve as monopole radiators, and the horizontal cables form a capacitive top-load to increase the efficiency of the antenna. High power stations use variations on the umbrella antenna such as the "delta" and "trideco" antennas, or multiwire flattop (triatic) antennas. For low power transmitters, inverted-L and T antennas are used. A large loading coil is required at the antenna feed point to cancel the capacitive reactance of the antenna to make it resonant.
Medium wave
For medium-wave (AM) broadcasting, quarter-wave masts are between and high, depending on the frequency. Because such tall masts can be costly and uneconomic, other types of antennas are often used, which employ capacitive top-loading (electrical lengthening) to achieve equivalent signal strength with vertical masts shorter than a quarter wavelength. A "top hat" of radial wires is occasionally added to the top of mast radiators, to allow the mast to be made shorter. For local broadcast stations and amateur stations of under 5 kW, T- and L-antennas are often used, which consist of one or more horizontal wires suspended between two masts, attached to a vertical radiator wire. A popular choice for lower-powered stations is the umbrella antenna, which needs only one mast one-tenth wavelength or less in height. This antenna uses a single mast insulated from ground and fed at the lower end against ground. At the top of the mast, radial top-load wires are connected (usually about six) which slope downwards at an angle of 40–45 degrees as far as about one-third of the total height, where they are terminated in insulators and thence outwards to ground anchors. Thus the umbrella antenna uses the guy wires as the top-load part of the antenna. In all these antennas the smaller radiation resistance of the short radiator is increased by the capacitance added by the wires attached to the top of the antenna.
List of FM broadcast translators used as primary stations
The original rules established for translator stations by the Federal Communications Commission have been expanded to allow AM stations to operate FM translators, most commonly to expand nighttime service for stations with very low nighttime powers or which are limited to only broadcasting during daylight hours. The development of HD Radio digital sub-channels for FM stations led to a second expanded use for translators. Due to a lack of commercial receivers capable of receiving HD transmissions, a translator is now permitted to retransmit the programming of an FM station's secondary ("HD2") or tertiary ("HD3") signals. And unlike the original FM translators, an HD-relaying translator normally provides coverage for the same area as the HD transmission, and it is common for both the originating HD transmitter and its translator to be located on the same transmitting tower.
Random wire antenna
If used for transmitting, a random wire antenna usually will also require an antenna tuner, as it has an unpredictable impedance that varies with frequency. One side of the output of the tuner is connected directly to the antenna, without a transmission line, the other to a good earth ground. A quarter-wavelength sized wire works best, and unless fed through a unun, a half-wavelength will exceed the matching ability of most tuners. Even without a good earth, the antenna will also radiate, but it will do so by coupling capacitively to any nearby conducting material; nevertheless this is not recommended. The ground for a random wire antenna may be chosen by experimentation. Grounds could be returned to a nearby cold water pipe or a wire approximately one-quarter wavelength long, or can be replaced by randomly laid-out quarter-wavelength counterpoise wires attached to the ground connection.
Television antenna
Starting in 2006 many countries in the world switched from broadcasting using an older analog television standard to newer digital television (DTV). However generally the same broadcast frequencies are used, so the same antennas used for the older analog television will also receive the new DTV broadcasts. Sellers often claim to supply a special "digital" or "high-definition television" (HDTV) antenna advised as a replacement for an existing analog television antenna; at best this is misinformation to generate sales of unneeded equipment, at worst it may leave the viewer with a UHF-only antenna in a local market (particularly in North America) where some digital stations remain on their original high VHF frequencies.
Very low frequency
A major practical drawback to this band is that because of the length of the waves, full size resonant antennas (half wave dipole or quarter wave monopole antennas) cannot be built because of their physical height. Vertical antennas must be used because VLF waves propagate in vertical polarization, but a quarter-wave vertical antenna at 30 kHz would be high. So practical transmitting antennas are electrically short, a small fraction of a wavelength long. Due to their low radiation resistance (often less than one ohm) they are inefficient, radiating only 10% to 50% of the transmitter power at most, with the rest of the power dissipated in the antenna/ground system resistances. Very high power transmitters (~1 megawatt) are required for long distance communication, so the efficiency of the antenna is an important factor.
Low-power broadcasting
Unlike AM and FM, unlicensed use of television bands is prohibited for broadcasting. The amateur television channels do allow for some very limited non-entertainment transmissions however, with some repeaters airing NASA TV during Space Shuttle missions when they are not in local use.
Super high frequency
The wavelengths of SHF waves are small enough that they can be focused into narrow beams by high gain antennas from a half meter to five meters in diameter. Directive antennas at SHF frequencies are mostly aperture antennas, such as parabolic antennas (the most common type), dielectric lens, slot and horn antennas. Large parabolic antennas can produce very narrow beams of a few degrees or less, and often must be aimed with the aid of a boresight. For omnidirectional applications like wireless devices and cellphones, small dipoles or monopoles are used. The patch antenna is another type, often integrated into the skin of aircraft. Another type of antenna practical at microwave frequencies is the phased array, consisting of many dipoles or patch antennas on a flat surface, each fed through a phase shifter, which allows the array's beam to be steered electronically. The short wavelength requires great mechanical rigidity in large antennas, to ensure that the radio waves arrive at the feed point in phase.
Mast radiator
A mast radiator (or radiating tower) is a radio mast or tower in which the entire structure functions as an antenna. This design, first used in radiotelegraphy stations in the early 1900s, is commonly used for transmitting antennas operating at low frequencies, in the VLF, LF and MF ranges, in particular those used for AM broadcasting. The metal mast is electrically connected to the transmitter. Its base is usually mounted on a nonconductive support to insulate it from the ground. A mast radiator is a form of monopole antenna.
Air interface
Multiple links can be created in limited spectrum through FDMA, TDMA, or SDMA. Some advanced forms of transmission multiplexing combine frequency and time division approaches like OFDM or CDMA.
In cellular telephone communications, the air interface is the radio-frequency portion of the circuit between the cellular phone set or wireless modem (usually portable or mobile) and the active base station. As a subscriber moves from one cell to another in the system, the active base station changes periodically. Each changeover is known as a handoff.Inverted F antenna use as mobile phone interface medium. In radio and electronics, an antenna (plural antennae or antennas), or aerial, is an electrical device which converts electric power into radio waves, and vice versa.[1] It is usually used with a radio transmitter or radio receiver. In transmission, a radio transmitter supplies an electric current oscillating at radio frequency (i.e. a high frequency alternating current (AC)) to the antenna's terminals, and the antenna radiates the energy from the current as electromagnetic waves (radio waves).
An antenna focuses the radio waves in a certain direction. Usually, this is called the main direction. Because of that, in other directions less energy wil be emitted. The gain of an antenna, in a given direction, is usually referenced to an (hypothetical) isotropic antenna, which emits the radiation evenly strong in all directions. The antenna gain is the power in the strongest direction divided by the power that would be transmitted by an isotropic antenna emitting the same total power. In this case the antenna gain (Gi) is often specified in dBi, or decibels over isotropic. 
Other reference antennas are also used, especially: •gain relative to a half-wave dipole (Gd), when the reference antenna is a half-wave dipole antenna;
•gain relative to a short vertical antenna (Gv), when the reference antenna is a linear conductor, much shorter than one quarter of the wavelength.
Microwave antenna
A microwave antenna is a physical transmission device used to broadcast microwave transmissions between two or more locations . In addition to broadcasting, antennas are also used in radar, radio astronomy and electronic warfare. A parabolic antenna is an antenna that uses a parabolic reflector, a curved surface with the cross-sectional shape of a parabola, to direct the radio waves. These devices range anywhere from 6" to more than 12' diameter depending on application and use.
TV and FM DX
For three nights in December 1978, astronomer Dr. Woodruff T. Sullivan III used the 305-metre Arecibo radio telescope to observe the Moon at a variety of frequencies. This experiment demonstrated that the lunar surface is capable of reflecting terrestrial band III (175 – 230 MHz) television signals back to earth. While not yet confirmed, FM broadcast EME reception may also be possible using the Arecibo dish antenna.
Technology of television
Although the BBC initially used Band I VHF at 45 MHz, this frequency is (in the UK) no longer in use for this purpose. Band II is used for FM radio transmissions. Higher frequencies behave more like light and do not penetrate buildings or travel around obstructions well enough to be used in a conventional broadcast TV system, so they are generally only used for MMDS and satellite television, which uses frequencies from 2 to 12 GHz. TV systems in most countries relay the video as an AM (amplitude-modulation) signal and the sound as an FM (frequency-modulation) signal. An exception is France, where the sound is AM.
Television antenna
It is sometimes desired to receive signals from transmitters which are not in the same direction. This can be achieved, for one station at a time, by using a rotator operated by an electric motor to turn the antenna as desired. Alternatively, two or more antennas, each pointing at a desired transmitter and coupled by appropriate circuitry, can be used. To prevent the antennas from interfering with each other, the vertical spacing between the booms must be at least half the wavelength of the lowest frequency to be received (Distance=λ/2). The wavelength of 54 MHz (Channel 2) is 5.5 meters (λ x f = c) so the antennas must be a minimum of 2.25 metres, or about 89 inches apart. It is also important that the cables connecting the antennas to the signal splitter/merger be exactly the same length, to prevent phasing issues, which cause ghosting with analog reception. That is, the antennas might both pick up the same station; the signal from the one with the shorter cable will reach the receiver slightly sooner, supplying the receiver with two pictures slightly offset. There may be phasing issues even with the same length of down-lead cable. Bandpass filters or "signal traps" may help to reduce this problem.
Antenna tuner
Transmitters with built-in antennas that only cover a narrow frequency band, such as cell phones and walkie-talkies, have an ATU circuit inside permanently set to work with the installed antenna. In communication stations like amateur radio stations and high power transmitters like radio broadcasting stations, the ATU is adjustable to accommodate changes in the frequency, antenna, or transmitter, and adjusting the ATU to match the transmitter to the antenna is an important procedure which is done after any work on the transmitter or antenna occurs. This adjustment is typically made using an instrument called an SWR meter, which measures the amount of power reflected back toward the transmitter.
Radio direction finder
RDF systems can be used with any radio source, although the size of the receiver antennas are a function of the wavelength of the signal; very long wavelengths (low frequencies) require very large antennas, and are generally used only on ground-based systems. These wavelengths are nevertheless very useful for marine navigation as they can travel very long distances and "over the horizon", which is valuable for ships when the line-of-sight may be only a few tens of kilometres. For aerial use, where the horizon may extend to hundreds of kilometres, higher frequencies can be used, allowing the use of much smaller antennas. An automatic direction finder, often capable of being tuned to commercial AM radio transmitters, is a feature of almost all modern aircraft.
UHF television broadcasting
Another effect due to the shorter wavelength is that UHF signals can pass through smaller openings than VHF. These openings are created by any metal in the area, including lines of nails or screws in the roof and walls, electrical wiring, and the frames of doors and windows. A metal-framed window will present almost no barrier to a UHF signal, while a VHF signal may be attenuated or strongly diffracted. For strong signals, UHF antennas mounted beside the television are relatively useful, and medium-distance signals, , can often be picked up by attic mounted antennas.
Dipole antenna
Half-wave folded dipoles are often used for FM radio antennas; versions made with twin lead which can be hung on an inside wall often come with FM tuners. The T2FD antenna is a folded dipole. They are also widely used as driven elements for rooftop Yagi television antennas.
FM broadcasting in Japan
Second-hand automobiles imported from Japan contain a radio designed for the Japanese FM band, and importers often fit a "converter" to down-convert the 87.5 to 108.0 MHz band to the frequencies that the radio can accept. In addition to showing an incorrect frequency, there are two other disadvantages that can result in undesired performance; the converter cannot down-convert in full the regular international FM band (up to 20.5 MHz wide) to the only 14 MHz wide Japanese band (unless the converter incorporates two user-switchable down-convert modes), and the original antenna may perform poorly on the higher FM band. Another problem is that RDS is not used in Japan, whereas most modern car radios available in Europe use this system. Also the converter may not allow pass-through of the MW band (if desired). A better solution is to replace the radio and antenna with ones designed for the country where the car will be used, but this can be difficult where custom-built radios are fitted.
Home wiring
Antenna types vary depending on location; an urban area with nearby transmitters will require a smaller antenna than a rural site with distant stations. The antenna is often mounted outdoors on the roof or a tower. A coaxial or twinlead cable is run from the antenna to the location where the television is located. One common type of cable is designated RG-6 Tri-shield or quad-shield cable. The cable is terminated on a television outlets, typically an F connector mounted on a face plate. If there are multiple outlets, an RF splitter is used to divide the signal among them; outlets on the splitter are connected to television outlets at each location (living room, rec room, bedrooms, den, for example). RF splitters come with different types; some include amplifiers for multiple outlets.
Radio masts and towers
In some cases, it is possible to install transmitting antennas on the roofs of tall buildings. In North America, for instance, there are transmitting antennas on the Empire State Building, the Willis Tower, 4 Times Square, and One World Trade Center. The North Tower of the original World Trade Center also had a telecommunications antenna atop its roof, constructed in 1978–1979, and began transmission in 1980. When the buildings collapsed, several local TV and radio stations were knocked off the air until backup transmitters could be put into service. Such facilities also exist in Europe, particularly for portable radio services and low-power FM radio stations. In London, the BBC erected in 1936 a mast for broadcasting early television on one of the towers of a Victorian building, the Alexandra Palace. It is still in use.
T-antenna
The "multiple-tuned flattop antenna" is a variant of the T antenna used in high power low frequency transmitters to reduce ground power losses. It consists of a long capacitive top-load consisting of multiple parallel wires supported by a line of transmission towers, sometimes several miles long. Several vertical radiator wires hang down from the top-load, each attached to its own ground through a loading coil. The antenna is driven either at one of the radiator wires, or more often at one end of the top-load, by bringing the wires of the top-load diagonally down to the transmitter. Although the vertical wires are separated, the distance between them is small compared to the length of the LF waves, so the currents in them are in phase and they can be considered as one radiator. Since the antenna current flows into the ground through "N" parallel loading coils and grounds rather than one, the equivalent loading coil and ground resistance, and therefore the power dissipated in the loading coil and ground, is reduced to 1/"N" that of a simple T antenna. The antenna was used in the powerful radio stations of the wireless telegraphy era but has fallen out of favor due to the expense of multiple loading coils.
Antenna rotator
Rotators are commonly used in amateur radio and military communications installations. They are also used with TV and FM antennas, where stations are available from multiple directions, as the cost of a rotator is often significantly less than that of installing a second antenna to receive stations from multiple directions.
Folded unipole antenna
A typical AM broadcast antenna is a series-fed monopole antenna above a ground system. The ground system normally comprises 120 buried copper or phosphor bronze radial wires at least one-quarter wavelength long and a ground-screen in the immediate vicinity of the tower. All the ground system components are bonded together, usually by brazing or using coin silver solder to minimize corrosion. These antennas have insulated bases. If required, insulated guy wires are used. Radio frequency power is fed across the base insulator between the ground system and the tower itself. In the US, the Federal Communications Commission (FCC) required that the transmitter power measurements for a single series-fed tower calculated at this feed point as the current squared multiplied by the resistive part of the feed-point impedance.
Naval Radio Transmitter Facility (NRTF) Niscemi
The joint American, Italian, and NATO facility houses an AN/FRT-95A Low Frequency Radio Transmitting System, hosts a USAF HF SCOPE Command, part of the High Frequency (HF) Global Communications System (HFGCS) and a US Navy MUOS Ground Station. The surrounding antenna field supports one 827 foot LF antenna, 44 HF (3–30 MHz) antennas, three MUOS Earth Terminal parabolic antennas, and 2 UHF Directional Helical antennas for satellite direction finding.
Several different types of HF antenna are installed, though the majority are no longer in use. 116 Antenna towers are installed which hold aloft 35 antenna transmission lines. Antenna types include four Horizontal Log Periodic (HLPA) with 2 tall towers each, four rotatable log periodic (RLPA), seven Horizontal Omnidirectional Broadband (HOBA) each with 4 antenna towers, seven High Take-Off Angle (HTOA), 11 Dual Mode (DM) antennae held aloft with 7 towers each, 1 Spira-cone, and 10 decommissioned Horizontal/Vertical HF Loop Antennae. The LF Transmitter uses non-line-of-sight propagation for communication with submarines.
Amateur television
The 23-centimeter band (1240-1300 MHz) is the third highest frequency band available for ATV. Analog big-dish satellite television (TVRO) receivers may be re-purposed for inexpensively receiving ATV in this band. Such receivers can decode FM television when an outdoor antenna is connected to the LNB input. Due to the low cost and ease of repurposing old analog satellite receivers, this is the most popular band for FM amateur TV.
TV radio
For the increasingly uncommon analog television standard, the audio for each TV channel is broadcast on a separate frequency band near the video signal frequency band (refer to article NTSC, Transmission modulation scheme). This audio signal can be heard separate from the video, using standard analog FM radios equipped with the appropriate tuning circuits.
Radio masts and towers
A tethered balloon or a kite can serve as a temporary support. It can carry an antenna or a wire (for VLF, LW or MW) up to an appropriate height. Such an arrangement is used occasionally by military agencies or radio amateurs. The American broadcasters TV Martí broadcast a television program to Cuba by means of such a balloon.
Folded unipole antenna
It has seen much use for medium wave (AM broadcast) stations in the United States, and other countries as well. When an AM station (mediumwave, long antennas) shares a tower with FM transmitters (VHF, short antennas), the folded-unipole is often a good choice. Since the base of the tower connects to the ground system, the transmission lines to any antennas mounted on the tower can run up the side of the tower without requiring isolation, even though the tower itself carries mediumwave current.
The folded unipole antenna was first devised for broadcast use by John H. Mullaney, an American radio broadcast pioneer, and consulting engineer. It was designed to solve some difficult problems with existing medium wave (MW), frequency modulation (FM), and amplitude modulation (AM) broadcast antenna installations.
Channel 5 (UK)
The British frequency plan had only allowed for four channels to be transmitted over the whole of the UK using analogue terrestrial transmitters, but the ITC identified that UHF channels 35 and 37 could provide coverage of around 70% of the UK population. These channels were used by many domestic video recorders for RF connection to television sets. Before the channel could launch, the broadcaster had to provide over-the-phone instructions or visit any home that complained to either retune the video recorder or fit a filter to completely block the Channel 5 signal.
Antenna (radio)
Generally an antenna will not have a feed-point impedance that matches that of a transmission line; a matching network between antenna terminals and the transmission line will improve power transfer to the antenna. The matching network may also limit the usable bandwidth of the antenna system. It may be desirable to use tubular elements, instead of thin wires, to make an antenna; these will allow a greater bandwidth. Or, several thin wires can be grouped in a "cage" to simulate a thicker element. This widens the bandwidth of the resonance.
Yagi–Uda antenna
After World War 2, the advent of television broadcasting motivated extensive development of the Yagi–Uda antenna as a rooftop television reception antenna in the VHF and UHF bands, and to a lesser extent an FM radio antenna. Until the development of the log-periodic antenna in the 1960s, it was the only type of antenna that could give adequate fringe reception in areas far from the television transmitter. A major drawback was the Yagi's inherently narrow bandwidth. Very complicated Yagi designs were developed to give adequate gain over the broad television bands. TV antennas are still a major application of the Yagi antenna.
Television station
VHF stations often have very tall antennas due to their long wavelength, but require much less effective radiated power (ERP), and therefore use much less transmitter power output, also saving on the electricity bill and emergency backup generators. In North America, full-power stations on band I (channels 2 to 6) are generally limited to 100 kW analog video (VSB) and 10 kW analog audio (FM), or 45 kW digital (8VSB) ERP. Stations on band III (channels 7 to 13) can go up by 5dB to 316 kW video, 31.6 kW audio, or 160 kW digital. Low-VHF stations are often subject to long-distance reception just as with FM. There are no stations on Channel 1.
Multichannel Multipoint Distribution Service
The BRS band uses microwave frequencies from 2.5 GHz to 2.7 GHz. Reception of BRS-delivered television and data signals is done with a rooftop microwave antenna. The antenna is attached to a down-converter or transceiver to receive and transmit the microwave signal and convert them to frequencies compatible with standard TV tuners (much like on satellite dishes where the signals are converted down to frequencies more compatible with standard TV coaxial cabling), some antennas use an integrated down-converter or transceiver. Digital TV channels can then be decoded with a standard cable set-top box or directly for TVs with integrated digital tuners. Internet data can be received with a standard DOCSIS Cable Modem connected to the same antenna and transceiver.
Amateur radio
In a few cases, a national telecommunication agency may also allow hams to use frequencies outside of the internationally allocated amateur radio bands. In Trinidad and Tobago, hams are allowed to use a repeater which is located on 148.800 MHz. This repeater is used and maintained by the National Emergency Management Agency (NEMA), but may be used by radio amateurs in times of emergency or during normal times to test their capability and conduct emergency drills. This repeater can also be used by non-ham NEMA staff and REACT members. In Australia and New Zealand ham operators are authorized to use one of the UHF TV channels. In the U.S., amateur radio operators providing essential communication needs in connection with the immediate safety of human life and immediate protection of property when normal communication systems are not available may use any frequency including those of other radio services such as police and fire and in cases of disaster in Alaska may use the statewide emergency frequency of 5167.5 kHz with restrictions upon emissions.
800 MHz frequency band
Essentially there are two types of interference sources in the 800 MHz band: The LTE base stations and the mobile terminals — handsets, tablets, dongles — which are sometimes close to TV equipment. Although the base stations may be relatively far away from the TV equipment they may be adjacent to the TV antenna, or if further away they may be in the 'beam' of the TV antenna, i.e. in the direction which the TV antenna points, and considerably closer than the TV transmitter which it is desired to receive resulting in a high level of interfering signal in the TV system. In the case of apartments, hotels, schools, colleges, offices, etc. with communal TV antenna systems the base station may be very close indeed, even on the same roof.
T-antenna
A T-antenna, T-aerial, flat-top antenna, or top-hat antenna is a capacitively loaded monopole wire radio antenna used in the VLF, LF, MF and shortwave bands. T-antennas are widely used as transmitting antennas for amateur radio stations, long wave and medium wave broadcasting stations. They are also used as receiving antennas for shortwave listening.
FM broadcasting
FM transmitters have been used to construct miniature wireless microphones for espionage and surveillance purposes (covert listening devices or so-called "bugs"); the advantage to using the FM broadcast band for such operations is that the receiving equipment would not be considered particularly suspect. Common practice is to tune the bug's transmitter off the ends of the broadcast band, into what in the United States would be TV channel 6 (<87.9 MHz) or aviation navigation frequencies (>107.9 MHz); most FM radios with analog tuners have sufficient overcoverage to pick up these slightly-beyond-outermost frequencies, although many digitally tuned radios have not.
2-meter band
Much of 2-meter FM operation uses a radio repeater, a radio receiver and transmitter that instantly retransmits a received signal on a separate frequency. Repeaters are normally located in high locations such as a tall building or a hill top overlooking expanses of territory. On VHF frequencies such as 2-meters, antenna height greatly influences how far one can talk. Typical reliable repeater range is about . Some repeaters in unusually high locations, such as skyscrapers or mountain tops, can be usable as far out as . Reliable range is very dependent on the height of the repeater antenna and also on the height and surroundings of the handheld or mobile unit attempting to access to the repeater. Line of sight would be the ultimate in reliability. The typical hand held two meter FM transceiver produces about 5 watts of transmit power. Stations in a car or home provide higher power, 25 to 75 watts, and may use a simple vertical antenna mounted on a pole or on the rooftop of a house or a vehicle.
Antenna array
Small antennas around one wavelength in size, such as quarter-wave monopoles and half-wave dipoles, don't have much directivity (gain); they are omnidirectional antennas which radiate radio waves over a wide angle. To create a directional antenna (high gain antenna), which radiates radio waves in a narrow beam, two general techniques can be used. One technique is to use reflection by large metal surfaces such as parabolic reflectors or horns, or refraction by dielectric lenses to change the direction of the radio waves, to focus the radio waves from a single low gain antenna into a beam. This type is called an "aperture antenna". A parabolic dish is an example of this type of antenna.
Yagi–Uda antenna
Also called a "beam antenna", or "parasitic array", the Yagi is very widely used as a high-gain antenna on the HF, VHF and UHF bands. It has moderate to high gain which depends on the number of elements used, typically limited to about 20 dBi, linear polarization, unidirectional (end-fire) beam pattern with high front-to-back ratio of up to 20 db. and is lightweight, inexpensive and simple to construct. The bandwidth of a Yagi antenna, the frequency range over which it has high gain, is narrow, a few percent of the center frequency, and decreases with increasing gain, so it is often used in fixed-frequency applications. The largest and best-known use is as rooftop terrestrial television antennas, but it is also used for point-to-point fixed communication links, in radar antennas, and for long distance shortwave communication by shortwave broadcasting stations and radio amateurs.
Television antenna
The television broadcast bands are too wide in frequency to be covered by a single antenna, so either separate antennas are used for the VHF and UHF bands, or a combination (combo) VHF/UHF antenna. A VHF/UHF antenna is really two antennas feeding the same feedline mounted on the same support boom. Longer elements which pick up VHF frequencies are located at the "back" of the boom and often function as a log-periodic antenna. Shorter elements which receive the UHF stations are located at the "front" of the boom and often function as a Yagi antenna.
Low frequency
For broadcasting stations, directional antennas are often required. They consist of multiple masts, which often have the same height. Some longwave antennas consist of multiple mast antennas arranged in a circle with or without a mast antenna in the center. Such antennas focus the transmitted power toward ground and give a large zone of fade-free reception. This type of antenna is rarely used, because they are very expensive and require much space and because fading occurs on longwave much more rarely than in the medium wave range. One antenna of this kind was used by transmitter Orlunda in Sweden.
Portofino transmitter
Portofino transmitter is a facility for FM-/AM-/TV-broadcasting near Portofino in Italy.
Portofino transmitter uses for the mediumwave transmitter, which works on 1575 kHz with 50 kW
a very unusual antenna, which consists of a wire which is fixed on a rope that is spun over a distance of 590 metres between a rock anchor and a 130 metres tall lattice tower, which carries the FM-/TV-broadcasting antennas.
This may be the only broadcasting transmitter in Europe, which uses a wire span over a valley as part of the antenna system.
Close to the main tower, there is a second lattice tower with triangular cross section.
Citizens band radio
The maximum power allowable on the MPT 1320 27/81 system was 4 watts (in common with the American system), although initially radios were equipped to reduce output power by 10 dB (to 0.4 watts) if the antenna was mounted more than 7 meters above ground level. The power-reduction switch is also useful in reducing TV interference. MPT 1320 also restricted antennas to a maximum length of 1.5 meters, with base loading being the only type permitted for 27 MHz operation. Over the next several years antenna regulations were relaxed, with antenna length increasing to 1.65 meters and centre- or top-loading of the main radiating element permitted. On September 1, 1987 the UK added the usual 40 frequencies (26.965–27.405 MHz) used worldwide, for a total of 80 channels at 27 MHz; antenna regulations were further relaxed, and the 934 MHz band was withdrawn in 1998.
Television antenna
Antennas are commonly placed on rooftops, and sometimes in attics. Placing an antenna indoors significantly attenuates the level of the available signal. Directional antennas must be pointed at the transmitter they are receiving; in most cases great accuracy is not needed. In a given region it is sometimes arranged that all television transmitters are located in roughly the same direction and use frequencies spaced closely enough that a single antenna suffices for all. A single transmitter location may transmit signals for several channels. CABD (communal antenna broadcast distribution) is a system installed inside a building to receive free-to-air TV/FM signals transmitted via radio frequencies and distribute them to the audience.
Direction finding
RDF systems can be used with any radio source, although very long wavelengths (low frequencies) require very large antennas, and are generally used only on ground-based systems. These wavelengths are nevertheless used for marine radio navigation as they can travel very long distances "over the horizon", which is valuable for ships when the line-of-sight may be only a few tens of kilometres. For aerial use, where the horizon may extend to hundreds of kilometres, higher frequencies can be used, allowing the use of much smaller antennas. An automatic direction finder, which could be tuned to radio beacons called non-directional beacons or commercial AM radio broadcasters, was until recently, a feature of most aircraft, but is now being phased out
HD Radio
In addition to the controversial practice of converting the HD Radio-only secondary channels of a primary station into analog FM in areas where the primary station's signal can already readily be received, translators can also be used in a more traditional manner to extend the range of the full content of the primary station, including the unmodified main signal and any HD radio sub-channels, in areas where the station has poor coverage or reception, as is done at K202BD in Manti, Utah, which rebroadcasts both the analog and digital signals of KUER from Salt Lake City. In order to do this, HD Radio may be passed along from the main station via a "bent pipe" setup, where the translator simply makes a frequency shift of the entire channel, often by heterodyning it through the use of an intermediate frequency. This may require an increase in bandwidth in both the amplifier and radio antenna if they are too narrowband to pass the wider signal, meaning one or both would have to be replaced. Baseband translators which use a separate receiver and transmitter require an HD Radio transmitter, just as does the main station. Translators are not required to pass through HD Radio, and the vast majority of existing translators which repeat FM stations running hybrid HD Radio signals do not repeat the HD Radio part of the broadcast due to technical limitations in equipment designed before the prominence of HD Radio.
TV tuner card
While most TV tuners are limited to the radio frequencies and video formats used in the country of sale, many TV tuners used in computers use DSP, so a firmware upgrade is often all that's necessary to change the supported video format. Many newer TV tuners have flash memory big enough to hold the firmware sets for decoding several different video formats, making it possible to use the tuner in many countries without having to flash the firmware. However, while it is generally possible to flash a card from one analog format to another due to the similarities, it is generally not possible to flash a card from one digital format to another due to differences in decode logic necessary.
Amateur radio
Fast scan amateur television has gained popularity as hobbyists adapt inexpensive consumer video electronics like camcorders and video cards in PCs. Because of the wide bandwidth and stable signals required, amateur television is typically found in the 70 cm (420–450 MHz) frequency range, though there is also limited use on 33 cm (902–928 MHz), 23 cm (1240–1300 MHz) and higher. These requirements also effectively limit the signal range to between 20 and 60 miles (30–100 km).
Helical antenna
Specialized enlarged normal-mode helical antennas are used for Base Station transmitters for FM radio and television broadcasting stations on the VHF and UHF bands.
History of radio
In 1933, FM radio was patented by inventor Edwin H. Armstrong. FM uses frequency modulation of the radio wave to reduce static and interference from electrical equipment and the atmosphere. In 1937, W1XOJ, the first experimental FM radio station, was granted a construction permit by the US Federal Communications Commission (FCC). In the 1930s, regular analog television broadcasting began in some parts of Europe and North America. By the end of the decade there were roughly 25,000 all-electronic television receivers in existence worldwide, the majority of them in the UK. In the US, Armstrong's FM system was designated by the FCC to transmit and receive television sound.
Log-periodic antenna
One large application for LPDAs is in rooftop terrestrial television antennas, since they must have large bandwidth to cover the wide television bands of roughly 54–88 and 174–216 MHz in the VHF and 470–890 MHz in the UHF while also having high gain for adequate fringe reception. One widely used design for television reception combined a Yagi for UHF reception in front of a larger LPDA for VHF.
Monopole antenna
The ground plane used with a monopole may be the actual earth; in this case the antenna is mounted on the ground and one side of the feedline is connected to an earth ground at the base of the antenna. This design is used for the mast radiator antennas employed in radio broadcasting at low frequencies, as well as other low frequency antennas such as the T-antenna and umbrella antenna. At VHF and UHF frequencies the size of the ground plane needed is smaller, so artificial ground planes are used to allow the antenna to be mounted above the ground. A common type of monopole antenna at these frequencies consists of a quarter-wave whip antenna with a ground plane consisting of several wires or rods radiating horizontally or diagonally from its base; this is called a ground-plane antenna. At gigahertz frequencies the metal surface of a car roof or airplane body makes a good ground plane, so car cell phone antennas consist of short whips mounted on the roof, and aircraft communication antennas frequently consist of a short conductor in an aerodynamic fairing projecting from the fuselage; this is called a "blade antenna". The most common antenna used in mobile phones is the inverted-F antenna, which is a variant of the inverted-L monopole. Bending over the antenna saves space and keeps the it within the bounds of the mobile's case but the antenna then has a very low impedance. To improve the match the antenna is not fed from the end, rather some intermediate point, and the end is grounded instead. The quarter-wave whip and rubber ducky antennas used with handheld radios such as walkie-talkies and cell phones are also monopole antennas. These don't use a ground plane, and the ground side of the transmitter is just connected to the ground connection on its circuit board. The hand and body of the person holding them may function as a rudimentary ground plane.
Digital terrestrial television in the United States
Within a distance of 35 to 40 miles from the broadcast stations, it is possible that a simple antenna (such as "rabbit ears") may be adequate to receive a DTV broadcast signal OTA—at least some of the time for some of the channels. Any television equipped with an ATSC tuner may display DTV broadcasts properly. Some customers discovered that terrain, trees, rain, snow, wind, and movement of people around the room interfere with reception to one degree or another, from signals breaking up to total loss of signal. (Few ATSC-equipped televisions or converter boxes have internal antennas, in contrast to analog sets available in years past).
Television receive-only
Large dishes have higher antenna gain, which can be an advantage when used with DBS signals such as Dish Network and DirecTV, virtually eliminating rain fade. Restored dishes fitted with block upconverters can be used to transmit signals as well. BUDs can still be seen at antenna farms for these reasons, so that video and backhauls can be sent to and from the television network with which a station is affiliated, without interruption due to inclement weather. BUDs are also still useful for picking-up weak signals at the edge of a satellite's broadcast "footprint" – the area at which a particular satellite is aimed. For this reason, BUDs are helpful in places like Alaska, or parts of the Caribbean.
Amateur radio
Linked repeater systems, however, can allow transmissions of VHF and higher frequencies across hundreds of miles. Repeaters are usually located on heights of land or tall structures and allow operators to communicate over hundreds of miles using hand-held or mobile transceivers. Repeaters can also be linked together by using other amateur radio bands, landline, or the Internet.
Amateur radio satellites can be accessed, some using a hand-held transceiver (HT), even, at times, using the factory "rubber duck" antenna. Hams also use the moon, the aurora borealis, and the ionized trails of meteors as reflectors of radio waves. Hams can also contact the International Space Station (ISS) because many astronauts and cosmonauts are licensed as amateur radio operators.
Corner reflector antenna
Corner reflector antennas are widely used for UHF television receiving antennas, point-to-point communication links and data links for wireless WANs, and amateur radio antennas on the 144, 420, and 1296 MHz bands. Corner reflector antennas radiate linearly polarized radio waves and can be mounted for either horizontal or vertical polarization.
Turnstile antenna
A later innovation involved changing the shape of the dipole elements, from simple rods to broader shapes, to increase the bandwidth of the antenna. Early TV broadcast antennas used "cigar shaped" elements, shown in image of 1939 RCA Empire State Building antenna above. A common shape today is the "batwing" or "superturnstile" antenna, used for television broadcasting in the VHF or UHF bands The "batwing" shape of each element produces an antenna with wide impedance bandwidth. Up to eight batwing antennas are usually stacked vertically and fed in phase to make a high gain omnidirectional antenna for TV broadcasting. The wide bandwidth was needed at the low VHF analog TV broadcast band, as the 6 MHz TV channel bandwidth was about 10% of the frequency.
Shower radio
Shower radios can be paired with FM transmitters since it can allow people who listen to their iPod or similar to be able to enjoy their favorite album or playlist while protecting their iPod, smartphone or other portable media player in a dry environment not too far from a shower. For this reason, most portable media players aren't water-resistant enough to be used in showers, sometimes FM transmitters can be used with desktop computers and laptop computers in a room not too far from the bathroom paired with an FM transmitter, though bluetooth serves a somewhat similar purpose for other shower radios that support bluetooth.
Tuner (radio)
Before the use of solid-state frequency synthesizers, covering the broad range of TV signal frequencies with a single tuned circuit and sufficient precision was uneconomic. Television channel frequencies were non-contiguous, with many non-broadcast services interleaved between VHF channels 6 and 7 in North America, for example. Instead, TV tuners of the era incorporated multiple sets of tuned circuits for the main signal path and local oscillator circuit. These "turret" tuners mechanically switched the receiving circuits by rotating a knob to select the desired channel. Channels were presented in fixed sequence, with no means to skip channels unused in a particular area. When UHF TV broadcasting was made available, often two complete separate tuner stages were used, with separate tuning knobs for selection of VHF band and UHF band channels. To allow for a small amount of drift or misalignment of the tuner with the actual transmitted frequency, tuners of that era included a "fine tuning" knob to allow minor adjustment for best reception. The combination of high frequencies, multiple electrical contacts, and frequent changing of channels in the tuner made it a high maintenance part of the television receiver, as relatively small electrical or mechanical problems with the tuner would make the set unusable.
Radio
An "antenna" (or "aerial") is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver. In transmission, a radio transmitter supplies an electric current oscillating at radio frequency (i.e. high frequency AC) to the antenna's terminals, and the antenna radiates the energy from the current as electromagnetic waves (radio waves). In reception, an antenna intercepts some of the power of an electromagnetic wave in order to produce a tiny voltage at its terminals, that is applied to a receiver to be amplified. Some antennas can be used for both transmitting and receiving, even simultaneously, depending on the connected equipment.
Mosonmagyaróvár
East of Mosonmagyaróvár at , there is a broadcasting station for AM and FM. The AM transmitter, which works on 1116 kHz with 2.2 kW uses as antenna a mast radiator, the FM-transmitter a free-standing lattice tower.
Sony Ericsson W205
The W205 contains an FM radio with RDS and an integrated antenna. The ability is provided to record radio either onto the 5 MB of internal memory or up to 2GB of external memory to the Memory Stick Micro (M2) memory card. Such recordings can also be saved and used as ringtones. Activation of the FM radio requires a FastPort-compatible headset connected to the phone; the headset is required to function as an antenna.
Radio receiver
The antenna may be enclosed inside the receiver's case, as with the ferrite loop antennas of AM radios and the flat inverted F antenna of cell phones; attached to the outside of the receiver, as with whip antennas used on FM radios, or mounted separately and connected to the receiver by a cable, as with rooftop television antennas and satellite dishes.
Observation tower
Also some radio towers were so built that they can be used apart from their function as transmitting tower also as observation tower. A condition for this is a sufficiently stable construction, which permits a permanent safe visitor entrance without interruption of the transmission services. This is the case for towers for radio services in the UHF/VHF-range the case, not however for most types of radio towers for long and medium wave, why a use of these structures as observation tower is impossible in most cases. That the use of a tower as radio tower for medium wave and observation tower not well fits, showed up in Radio Tower Berlin, which originally carried together with an 80 metres high mast a t-antenna for medium wave and stands on insulators. However one notices at the first experimental transmissions that at the tower voltages would arise, which would have unpleasant consequences for visitors and so the tower was grounded by the elevator shaft. However this shifted direction of main beam of transmitter away from actual supply area, the city of Berlin. As before World War II nearly whole radio traffic took place in the long -, medium and shortwave range, first after World War II with introduction of radio services in UHF/VHF-range required towers only acting as antenna carriers, radio towers with observation decks built. For this the closed reinforced concrete construction way was nearly always used. Radio towers with observation decks often serve for TV transmission or for radio relay link services and are called therefore usually TV tower or telecommunication tower. As a rule an elevator is available in these buildings for the visitors of the observation deck, as the observation deck lies usually very highly (mostly within the range between 50 and 200 metres, at some towers also more highly). Many of these towers have also a tower restaurant, which can be designed as revolving restaurant. While tower restaurants for the protection of the restaurant guests from the wind are in closed rooms, the prospect platform can be open or in a closed room. An open platform is more favourable for photographing, since no reflexes at the disk arise, while closed platforms are for many visitors more pleasant. Prospect outlooks on TV towers are opened only at certain times and their entrance is possible only under payment of an admission fee.
Transmitter station
They all have masts or towers to install antenna systems. In most cases, the mast is a passive structure to support the antennas. But in low frequency stations (such as AM radio), the mast itself may be the active antenna element. In such cases, the mast is isolated from the ground.("See" Monopole antenna). If the mast itself is an active antenna element, the ground can be covered by a mesh of wires or metal elements to create a reflecting ground. Most of the stations also have facility to receive microwave signals from a microwave link or a telecommunications satellite, (TVRO or RRO).
Antenna (radio)
Antennas for use over much broader frequency ranges are achieved using further techniques. Adjustment of a matching network can, in principle, allow for any antenna to be matched at any frequency. Thus the small loop antenna built into most AM broadcast (medium wave) receivers has a very narrow bandwidth, but is tuned using a parallel capacitance which is adjusted according to the receiver tuning. On the other hand, log-periodic antennas are "not" resonant at any frequency but can be built to attain similar characteristics (including feedpoint impedance) over any frequency range. These are therefore commonly used (in the form of directional log-periodic dipole arrays) as television antennas.
Panel antenna
Panel antennas are common at Ultra high frequency (UHF) frequencies, where they are often used for cellular/mobile base stations or wireless networking due to their size and directional properties. At VHF frequencies, such an antenna would be impractically large for most receiving applications unless implemented as no more than a two-bay design. Some full-power radio stations do use multiple panel antenna bays, installed one above the other on the side of a tall antenna tower, to provide a directional transmitter pattern on these frequencies.
Television antenna
Soon after television broadcasting switched from analog to digital broadcasting, indoor antennas have evolved beyond the traditional "rabbit ears." RCA is one manufacturer which has commercially sold a flat antenna. Flat antennas are very lightweight, very thin, and square-shaped like a thin notebook. They connect to televisions, or to digital converter boxes, with a single coaxial cable, and may be sold with an optional signal amplifier. Internally, the thin, flat square is a loop antenna, with its circular metallic wiring embedded into conductive plastic. The amplifier must be plugged into a power source, but the flat antenna does not require a power source.
FTA receiver
A toroidal antenna may be used with multiple LNB's to receive multiple satellites in various locations over a 40° arc. Unlike the single parabola of a standard satellite dish antenna (which is best adapted to focus one target satellite to a single point), the toroidal antenna uses a reflector pair to focus multiple signals to a line.
Television antenna
As discussed previously, antennas may be placed indoors where signals are strong enough to overcome antenna shortcomings. The antenna is simply plugged into the television receiver and placed conveniently, often on the top of the receiver ("set-top"). Sometimes the position needs to be experimented with to get the best picture. Indoor antennas can also benefit from RF amplification, commonly called a TV booster. Indoor antennas will never be an option in weak signal areas.
Low frequency
LF (longwave) broadcasting stations use mast antennas with heights of more than 150 meters or T-aerials. The mast antennas can be ground-fed insulated masts or upper-fed grounded masts. It is also possible to use cage antennas on grounded masts.
Television antenna
Outdoor antennas are highly directional. They have a narrow main lobe; that is, their maximum sensitivity (gain) is only achieved over a narrow angle along their axis, so they must be pointed at the transmitting antenna. This presents a problem when the television stations to be received are located in different directions. In this case two or more directional rooftop antennas each pointed at a different transmitter are often mounted on the same mast and connected to one receiver. An alternative is to use a single antenna mounted on a "rotator"; a remote servo system that rotates the antenna to a new direction when a dial next to the television is turned.
Monopole antenna
When used for radio broadcasting, the radio frequency power from the broadcasting transmitter is fed across the base insulator between the tower and a ground system. The ideal ground system for AM broadcasters comprises at least 120 buried copper or phosphor bronze radial wires at least one-quarter wavelength long and a ground-screen in the immediate vicinity of the tower. All the ground system components are bonded together, usually by welding, brazing or using coin silver solder to help reduce corrosion. Monopole antennas that use guy-wires for support are called masts in some countries. In the United States, the term “mast” is generally used to describe a pipe supporting a smaller antenna, so both self-supporting and guy-wire supported radio antennas are simply called monopoles if they stand alone. If multiple monopole antennas are used in order to control the direction of radio frequency (RF) propagation, they are called directional antenna arrays.
Amateur television
Additionally 33 cm is the lowest frequency band on which higher-quality frequency modulated amateur TV occurs. This format gives better picture quality than standard AM television. The FM television format used is identical to big dish analog satellite television and can be received by some tuners which can tune this low in frequency. Otherwise a specialized FM amateur TV receiver is needed.
TV radio
Direct analog frequency tuning of digital TV is further complicated by the fact that digital TV broadcasting allows the use of virtual channel numbers that are separate from the actual broadcast frequency channel. In this manner, on a fully digital receiver, a station may appear to be on VHF channel 13 but actually broadcasts on UHF channel 33. This complexity is hidden from the users of fully digital receivers, but would be exposed to the user of an analog tuner with a subchannel selector.
HD Radio
Stations can transmit HD Radio through their existing antennas using a diplexer as on AM, or are permitted by the FCC to use a separate antenna at the same location, or at a site licensed as an analog auxiliary, provided it is within a certain distance and height referenced to the analog main signal. This limitation assures that the two have about the same broadcast range, and that they maintain the proper ratio of signal strength to each other so as not to cause destructive interference with each other at any given location where they may be received.
Diplexer
Diplexers are also used in the home to allow a direct broadcast satellite TV dish antenna and a terrestrial TV antenna (local broadcast channels) to share one coaxial cable. The dish antenna occupies the high frequencies (typically 950 to 1450 MHz), and the TV antenna uses lower television channel frequencies (typically 50 to 870 MHz). In addition, the satellite also gets a DC to low frequency band to power the dish's block converter and select the dish antenna polarization (e.g., voltage signaling or DiSEqC). The diplexer is useful in homes that are already wired with one cable, because it eliminates the need to install a second cable. For the diplexer to work, the existing cable must be able to pass the satellite frequencies with little loss. Older TV installations may use a solid dielectric RG-59 cable, and that cable may be inadequate. RG-6 cable is typically used for satellite feed lines.
Cassette deck
Cassette tape adaptors have been developed which allow newer media players to be played through existing cassette decks, in particular those in cars which generally do not have input jacks. These units do not suffer from reception problems from FM transmitter based system to play back media players through the FM radio, though supported frequencies for FM transmitters that aren't used on commercial broadcasters in a given region (e.g. any frequency below 88.1 in the US) somewhat eliminates that problem.
FM broadcast band
The original frequency allocation in North America used by Edwin Armstrong used the frequency band from 42 through 50 MHz, but this allocation was changed to a higher band beginning in 1945. In Canada, the United States, Mexico, the Bahamas, etc., there are 101 FM channels numbered from "200" (center frequency 87.9 MHz) to "300" (center frequency 107.9 MHz), though these numbers are rarely used outside the fields of radio engineering and government.
The center frequencies of the FM channels are spaced in increments of 200 kHz. The frequency of 87.9 MHz, while technically part of TV channel 6 (82 to 88 MHz), is used by just two FM class-D stations in the United States. Portable radio tuners often tune down to 87.5 MHz, so that the same radios can be made and sold worldwide. Automobiles usually have FM radios that can tune down to 87.7 MHz, so that TV channel 6's audio at 87.75 MHz (±10 kHz) could be received, such as in Birmingham, Alabama, and Denver, Colorado. With the advent of digital television in the United States, this ability will soon be irrelevant when the remaining analog LPTV stations are required by the FCC to shut down or convert to digital by September 2015—but there are still analog television stations in the sparsely-populated regions of northern Canada. There are also analog TV stations on the other continents and on scores of different islands.
Fintona
Terrestrial Television along with FM & DAB radio can be received from the Brougher Mountain transmitter site, while similar TV & radio services from the Republic of Ireland can also be received by most people in Fintona. Satellite television is also popular, either through Freesat or the Sky subscription service . There are no cable operators in the village.
Microwave
Microwave radio is used in broadcasting and telecommunication transmissions because, due to their short wavelength, highly directional antennas are smaller and therefore more practical than they would be at longer wavelengths (lower frequencies). There is also more bandwidth in the microwave spectrum than in the rest of the radio spectrum; the usable bandwidth below 300 MHz is less than 300 MHz while many GHz can be used above 300 MHz. Typically, microwaves are used in television news to transmit a signal from a remote location to a television station from a specially equipped van. See broadcast auxiliary service (BAS), remote pickup unit (RPU), and studio/transmitter link (STL).
FM- and TV-mast Hosingen
The FM- and TV-mast Hosingen carries antennas at a height of 285 metres, pointed toward Germany. These antennas are used for transmitting the German-speaking program of RTL on 97,0 MHz with an ERP of 100 kW. The antennas for the transmission of the native radio station on 92,5 MHz with an ERP of 50 kW are mounted at a height of 237 metres. As transmission device for both frequencies, Telefunken S 3217 transmitters with an output power of 10 kW is used. For each frequency there is also a backup transmitter installed, with an output power of 10 kW, a Telefunken S 3152.
UHF television broadcasting
Because the antenna size is based on the wavelength, UHF broadcasting can be received with much smaller antennas than VHF while still having the same gain. For instance, Channel 2 in the North American television frequencies is at 54 MHz, which corresponds to a wavelength of 5.5 m, and thus requires dipole antenna about 2.75 m across. In comparison, the lowest channel in the UHF map, Channel 14, is on 470 MHz, a wavelength of 64 cm, or a dipole length of only 32 cm. A powerful VHF antenna using the log-periodic design might be as long as 3 m, while a UHF Yagi antenna with similar gain is often found placed in front of it, occupying perhaps 1 m. Modern UHF-only antennas often use the bedspread array and are less than a meter on a side.
Pocket FM
Pocket FM is intended for use in areas with poor or unreliable broadcasting infrastructure, and incorporates several design elements to support its operation in challenging situations. Radio stations typically use large transmitters to produce strong signals broadcast across large areas. However, large transmitters are very expensive, challenging to maintain, and provide highly visible targets for those wishing to sabotage, raid, hijack, or otherwise interrupt communications. The idea behind Pocket FM is to instead create a network of many small transmitters that can blanket an area. The first two versions had a range of , with version 3 up to , using only a antenna.
High-definition television
In the US, residents in the line of sight of television station broadcast antennas can receive free, over the air programming with a television set with an ATSC tuner (most sets sold since 2009 have this). This is achieved with a TV aerial, just as it has been since the 1940s except now the major network signals are broadcast in high definition (ABC, Fox, and Ion Television broadcast at 720p resolution; CBS, My Network TV, NBC, PBS at 1080i; and The CW at either resolution depending on the local affiliate). As their digital signals more efficiently use the broadcast channel, many broadcasters are adding multiple channels to their signals. Laws about antennas were updated before the change to digital terrestrial broadcasts. These new laws prohibit home owners' associations and city government from banning the installation of antennas.
Radio telescope
The range of frequencies in the electromagnetic spectrum that makes up the radio spectrum is very large. This means that the types of antennas that are used as radio telescopes vary widely in design, size, and configuration. At wavelengths of 30 meters to 3 meters (10 MHz - 100 MHz), they are generally either directional antenna arrays similar to "TV antennas" or large stationary reflectors with moveable focal points. Since the wavelengths being observed with these types of antennas are so long, the "reflector" surfaces can be constructed from coarse wire mesh such as chicken wire.
The increasing use of radio frequencies for communication makes astronomical observations more and more difficult (see Open spectrum).
Negotiations to defend the frequency allocation for parts of the spectrum most useful for observing the universe are coordinated in the Scientific Committee on Frequency Allocations for Radio Astronomy and Space Science.
Television antenna
The wavelength of a radio wave equals the speed of light (c) divided by the frequency. The elements of most television antennas are half-wave dipoles; metal rods half the wavelength of the signal they are intended to receive. The above frequency bands cover a 15:1 wavelength ratio, or almost 4 octaves. It is difficult to design a single antenna to receive such a wide wavelength range, and there is an octave gap from 216 to 470 MHz between the VHF and UHF frequencies. So traditionally separate antennas (or on outdoor antennas separate sets of elements on a single support boom) have have been used to receive the VHF and UHF channels. Most television stations broadcast in circular polarization, so that linearly polarized antennas can receive the signal equally well in any orientation.
TV and FM DX
VHF/UHF television and radio signals are normally limited to a maximum "deep fringe" reception service area of approximately in areas where the broadcast spectrum is congested, and about 50 percent farther in the absence of interference. However, providing favourable atmospheric conditions are present, television and radio signals sometimes can be received hundreds or even thousands of miles outside their intended coverage area. These signals are often received using a large outdoor antenna system connected to a sensitive TV or FM receiver, although this may not always be the case. Many times smaller antennas and receivers such as those in vehicles will receive stations farther than normal depending on how favourable conditions are.