How far can a radio station broadcast?
Telecommunication
The other meaning of the term "channel" in telecommunications is seen in the phrase communications channel, which is a subdivision of a transmission medium so that it can be used to send multiple streams of information simultaneously. For example, one radio station can broadcast radio waves into free space at frequencies in the neighborhood of 94.5 MHz (megahertz) while another radio station can simultaneously broadcast radio waves at frequencies in the neighborhood of 96.1 MHz. Each radio station would transmit radio waves over a frequency bandwidth of about 180 kHz (kilohertz), centered at frequencies such as the above, which are called the "carrier frequencies". Each station in this example is separated from its adjacent stations by 200 kHz, and the difference between 200 kHz and 180 kHz (20 kHz) is an engineering allowance for the imperfections in the communication system.
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.
International broadcasting
Most radio receivers in the world receive the mediumwave band (530 kHz to 1710 kHz), which at night is capable of reliable reception from 150 to 2,500 km distance from a transmitter. Mediumwave is used heavily all over the world for international broadcasting on a formal and informal basis.
Grimeton Radio Station
To achieve maximum range, like other transoceanic radiotelegraphy stations of this era it transmitted in the VLF band, at a frequency of 17.2 kilohertz and so the wavelength is approximately 17,442 meters. Even though the antenna is approximately 2km long, it is short compared with the wavelength and so it is not very efficient. The six antenna masts each have a 46m cross-arm at the top and are 127m high. Today they carry 8 antenna conductors although originally there were 12.
Sporadic E propagation
Communication distances of 800–2200 km can occur using a single E cloud. This variability in distance depends on a number of factors, including cloud height and density. MUF also varies widely, but most commonly falls in the 25 – 150 MHz range, which includes the FM broadcast band (87.5–108 MHz), Band I VHF television (American channels 2-6, Russian channels 1-3, and European channels 2-4, the latter no longer used in Western Europe), CB radio (27 MHz) and the amateur radio 2-meter, 4-meter, 6-meter, and 10-meter bands. Strong events have allowed propagation at frequencies as high as 250 MHz.
City of license
While becoming less meaningful over the decades, stations are still required to post a public file somewhere within 25 miles of the city, and to cover the entire city with a local signal. In the United States, a station's transmitter must be located so that it can provide a strong signal over nearly all of its "principal community" (5 mV/m or stronger at night for AM stations, 70 dbuV for FM, 35 dbu for DTV channels 2-6, 43 dbu for channels 7-13 and 48 dbu for channels 14+), even if it primarily serves another city. For example, American television station WTTV primarily serves Indianapolis; however, the transmitter is located farther south than the other stations in that city because it is licensed to Bloomington, 50 miles south of Indianapolis. In some cases, such as Jeannette, Pennsylvania-licensed WPCW 19, the FCC has waived this requirement; the station claimed that retaining an existing transmitter site 25.6 miles southeast of its new community of license of Jeannette would be in compliance with the Commission's minimum distance separation requirements (avoiding interference to co-channel WOIO 19 Shaker Heights). Another extreme example of a station's transmitter located far from the city of license is the FM station KPNT, formerly licensed to Ste. Genevieve, Missouri and transmitting from Hillsboro, but serving the St. Louis and Metro East market to the north. In 2015, the station was allowed by the FCC to move their city of license to Collinsville, Illinois and have a transmitter in St. Louis proper with a power decrease.
FM transmitter (personal device)
Being low-powered, most transmitters typically have a short range of 100–300 feet (30–100 metres), depending on the quality of the receiver, obstructions and elevation. Typically they broadcast on any FM frequency from 87.5 to 108.0 MHz in most of the world, 76.0 - 95.0 MHz for Japan, 65.0 - 74.2 MHz for Russia (or 88.1 to 107.9 MHz in the US and Canada).
Radio
In the early part of the 20th century, American AM radio stations broadcast with powers as high as 500 kW, and some could be heard worldwide; these stations' transmitters were commandeered for military use by the US Government during World War II. Currently, the maximum broadcast power for a civilian AM radio station in the United States and Canada is 50 kW, and the majority of stations that emit signals this powerful were grandfathered in (see List of 50 kW AM radio stations in the United States). In 1986 KTNN received the last granted 50,000-watt class A license. These 50 kW stations are generally called "clear channel" stations (not to be confused with Clear Channel Communications), because within North America each of these stations has exclusive use of its broadcast frequency throughout part or all of the broadcast day.
Radio Saint Helena
Radio Saint Helena (call-sign: "ZHH") was a local radio station serving the South Atlantic island of Saint Helena. Broadcasting on an AM frequency of 1548 kHz (194 m), the station was audible within a range of about 100 km from the island.
CIUT-FM
Today, CIUT broadcasts at 15 kilowatts from a transmitter on the top of First Canadian Place in Downtown Toronto. With greater signal power than generally found at other community radio stations, CIUT's broadcast reaches as far as Barrie to the north, Buffalo to the south, Kitchener to the west and Cobourg to the east.
Surface wave
Ground waves have been used in over-the-horizon radar, which operates mainly at frequencies between 2–20 MHz over the sea, which has a sufficiently high conductivity to convey them to and from a reasonable distance (up to 100 km or more; over-horizon radar also uses skywave propagation at much greater distances). In the development of radio, ground waves were used extensively. Early commercial and professional radio services relied exclusively on long wave, low frequencies and ground-wave propagation. To prevent interference with these services, amateur and experimental transmitters were restricted to the high frequencies (HF), felt to be useless since their ground-wave range was limited. Upon discovery of the other propagation modes possible at medium wave and short wave frequencies, the advantages of HF for commercial and military purposes became apparent. Amateur experimentation was then confined only to authorized frequencies in the range.
Apex (radio band)
Through the 1920s and 1930s, radio engineers and government regulators were slowly determining the transmission characteristics of various frequencies being evaluated for use by radio stations. In the United States, by 1930 the original AM broadcasting band consisted of 96 frequencies from 550 to 1500 kHz, with a 10 kHz spacing between adjacent assignments. On this band, a station's coverage during the daytime consisted exclusively of its groundwave signal, which for the most powerful stations might exceed 200 miles (320 kilometers), although it was significantly less for the average station. However, during the nighttime, changes in the ionosphere resulted in additional long distance skywave signals, that were commonly reflected for up to hundreds of kilometers.
FM broadcast band
The FM broadcast band, used for FM broadcast radio by radio stations, differs between different parts of the world. In Europe, Australia and Africa ((defined as International Telecommunication Union (ITU) region 1)), it spans from 87.5 to 108 megahertz (MHz) - also known as VHF Band II - while in the Americas (ITU region 2) it ranges from 88 to 108 MHz. The FM broadcast band in Japan uses 76 to 95 MHz. The International Radio and Television Organisation (OIRT) band in Eastern Europe is from 65.8 to 74.0 MHz, although these countries now primarily use the 87.5 to 108 MHz band, as in the case of Russia. Some other countries have already discontinued the OIRT band and have changed to the 87.5 to 108 MHz band.
Citizens band radio
Citizens band radio (also known as CB radio) is, in many countries, a system of short-distance radio communications between individuals typically on a selection of 40 channels within the 27 MHz (11 m) band. Citizens band is distinct from other personal radio service allocations such as FRS, GMRS, MURS, UHF CB and the Amateur Radio Service ("ham" radio). In many countries, CB operation does not require a license, and (unlike amateur radio) it may be used for business or personal communications. Like many other two-way radio services, citizens band channels are shared by many users. Only one station may transmit at a time; other stations must listen and wait for the shared channel to be available. It is customary for stations waiting to use a shared channel to broadcast the single word "Break" followed by the channel number, during a lull in the conversation. This informs people using the channel that others are waiting.
Radio One (New Zealand)
In the station's early years, its 100 Watt transmitter was located on the top of the campus's tallest building (the 11-storey Richardson Building, then known as the Hocken Building), but since the late 1980s it has had a transmitter on the top of Mount Cargill, 12 kilometres north of the campus. This gives the station a range which covers much of coastal Otago, from Oamaru to past Balclutha.
Community radio
They should be open to divergent opinions and divergent lifestyles regarding each of them. The average radius of reach is 1 km (covering a village and a neighborhood in particular). The use for the ideological-political end or to present a specific belief is not allowed. An entity that has interest can send the documents to the Statement of Interest Register (CDI). The requests received appeared in the National Grant Plan (PNO), later a notice will be opened with the documents that should be sent. This does not mean that the institution has obtained the radiofrequency, there will be a selection process to eliminate the competition. Even if after all it is authorized, it will have to be countersigned 90 days until the release of the National Congress, otherwise the applicant may require a provisional license.
Broadcast range
The "primary service area" is the area served by a station's strongest signal. The "city-grade contour" is 70 dBµ (decibels relative to one microvolt per meter of signal strength) or 3.16mV/m (millivolts per meter) for FM stations in the United States, according to Federal Communications Commission (FCC) regulations. This is also significant in broadcast law, in that a station must cover its city of license within this area, except for non-commercial educational and low-power stations.
TV and FM DX
Tropospheric propagation refers to the way radio signals travel through the lowest layer of the Earth's atmosphere, the troposphere, at altitudes up to about to 17 km (11 miles). Weather conditions in the lower atmosphere can produce radio propagation over greater ranges than normal. If a temperature inversion occurs, with upper air warmer than lower air, VHF and UHF radio waves can be refracted over the Earth's surface instead of following a straight-line path into space or into the ground. Such "tropospheric ducting" can carry signals for 800 km (500 miles) or more, far beyond usual range.
Medium frequency
Radio waves at MF wavelengths propagate via ground waves and reflection from the ionosphere ( called skywaves). Ground waves follow the contour of the Earth. At these wavelengths they can bend (diffract) over hills, and travel beyond the visual horizon, although they may be blocked by mountain ranges. Typical MF radio stations can cover a radius of several hundred miles from the transmitter, with longer distances over water and damp earth. MF broadcasting stations use ground waves to cover their listening areas.
Maximum usable frequency
In shortwave radio communication, a major mode of long distance propagation is for the radio waves to reflect off the ionized layers of the atmosphere and return diagonally back to Earth. In this way radio waves can travel beyond the horizon, around the curve of the Earth. However the refractive index of the ionosphere decreases with increasing frequency, so there is an upper limit to the frequency which can be used. Above this frequency the radio waves are not reflected by the ionosphere but are transmitted through it into space.
AN/UPN-1
Radar beacon AN/UPN-1, sometimes known as BUPS (Beacon, Ultra Portable, S-band), is an ultra-portable radio beacon for ground, paratroop or shipboard use having a range of 35 to 50 miles. The set is capable of being interrogated by airborne radars operating on beacon function and replying with a coded signal permitting the beacon to be located in range and azimuth. It is capable of transmitting five different codes, it transmits on 3256 Mc. (Megacycles [per second], now MHz (Megahertz)) and receives on 3333 Mc. peak power output is 50 Watts.
Broadcast range
The local terrain can also play a major role in limiting broadcast range. Mountain ranges block FM broadcasts, AM broadcasts, and TV broadcasts, and other signals in the VHF and especially UHF ranges, respectively. This terrain shielding occurs when the line of sight is blocked by something through which the radio waves cannot pass, particularly stone. At times this may be moot due to weather, such as when the tall cumulonimbus clouds of a squall line of thunderstorms reflect the signal over the top, like an extremely tall radio tower. Conversely, heavy rain may attenuate the range of even local stations. ATSC digital television is affected by wind and trees (even if not surrounding the transmitter or receiver locations), apparently related to its use of 8VSB modulation instead of COFDM.
Goa
DTH (Direct To Home) TV services are available from Dish TV, Videocon D2H, Tata Sky & DD Direct Plus. The All India Radio is the only radio channel in the state that broadcasts on both FM and AM bands. Two AM channels are broadcast, the primary channel at 1287 kHz and the Vividh Bharati channel at 1539 kHz. AIR's FM channel is called FM Rainbow and is broadcast at 105.4 MHz. A number of private FM radio channels are available, Big FM at 92.7 and Radio Indigo at 91.9 MHz. There is also an educational radio channel, Gyan Vani, run by IGNOU broadcast from Panaji at 107.8 MHz. In 2006, St Xavier's College, Mapusa, became the first college in the state to launch a campus community radio station "Voice of Xavier's".
Radio receiver
DAB radio stations work differently from AM or FM stations: a single DAB station transmits a wide 1,500 kHz bandwidth signal that carries from 9 to 12 channels from which the listener can choose. Broadcasters can transmit a channel at a range of different bit rates, so different channels can have different audio quality. In different countries DAB stations broadcast in either Band III (174–240 MHz) or L band (1.452–1.492 GHz).
Near vertical incidence skywave
Near vertical incidence skywave, or NVIS, is a skywave radio-wave propagation path that provides usable signals in the range between groundwave and conventional skywave distances—usually 30–400 miles (50–650 km). It is used for military and paramilitary communications, broadcasting, especially in the tropics, and by radio amateurs for nearby contacts circumventing line-of-sight barriers. The radio waves travel near-vertically upwards into the ionosphere, where they are refracted back down and can be received within a circular region up to 650 km from the transmitter. If the frequency is too high (that is, above the critical frequency of the ionospheric F layer), refraction fails to occur and if it is too low, absorption in the ionospheric D layer may reduce the signal strength.
Broadcast range
AM broadcasting stations have different issues, due to using the mediumwave band. Broadcast range in these stations is determined by ground conductivity, and the proper use and maintenance of grounding radials which act as a ground plane for the mast radiators used. Skywaves reflect off the ionosphere at a much greater distance above Earth's surface at night. This in turn causes mediumwave, most shortwave, and even longwave stations to travel much further at night, which is the side of the Earth where the solar wind pulls the ionosphere (and magnetosphere) away from the planet, instead of pushing toward it as on the day side. Because of this, many AM stations must cut power or go off-air at night, except for the very earliest stations still grandfathered on clear channels. Border blaster stations in northern Mexico also used this effect, along with very high-power transmitters, to extend their nighttime broadcast ranges well over the US/Mexico border and across most of the United States.
Campus radio
Most of the FM radio stations received higher-class licenses than ten watts, typically a few hundred watts. A few got several kilowatts, and a small handful got licenses in the range of tens of thousands, sometimes reaching up to maximum-power 100-kilowatt outlets. WRAS 88.5 FM and WREK 91.1 FM in Atlanta are the most powerful college radio station, operating at 100,000 watts. Still, due to strict class D regulations, some radio stations were prohibited from a wattage upgrade for possible signal interference with adjacent radio stations, such as KWUR 90.3 FM interfering with KWMU 90.7 FM in St. Louis, Missouri. KTUH 90.3 FM in Honolulu, Hawaii has had many increases in its wattage since they started broadcasting at 10 watts as a Non-commercial educational FM radio station in 1969. In 1984 KTUH received permission from the Board of Regents to increase to 100 watts of power. More recently, in 2001, KTUH began transmitting at 3000 watts of power. KTUH is heard on an island wide frequency in Honolulu, Hawaii from 90.1 FM, as well as online at KTUH.ORG and on digital cable channel 866.
Radiation
Very low frequency (VLF) refers to a frequency range of 30 Hz to 3 kHz which corresponds to wavelengths of 100,000 to 10,000 meters respectively. Since there is not much bandwidth in this range of the radio spectrum, only the very simplest signals can be transmitted, such as for radio navigation. Also known as the myriameter band or myriameter wave as the wavelengths range from ten to one myriameter (an obsolete metric unit equal to 10 kilometers).
WCIR-FM
The station has an effective radiated power of 5,000 watts, but the height above average terrain of the station is 452 meters (1484 feet), meaning the station broadcasts farther than a typical 5,000 watt radio station that broadcasts at normal height. As a result, the station can be heard as far as Charleston, West Virginia.
Radio
High power is useful in penetrating buildings, diffracting around hills, and refracting in the dense atmosphere near the horizon for some distance beyond the horizon. Consequently, 100,000-watt FM stations can regularly be heard up to away, and farther, , if there are no competing signals. A few old, "grandfathered" stations do not conform to these power rules. WBCT-FM (93.7) in Grand Rapids, Michigan, US, runs 320,000 watts ERP, and can increase to 500,000 watts ERP by the terms of its original license. Such a huge power level does not usually help to increase range as much as one might expect, because VHF frequencies travel in nearly straight lines over the horizon and off into space.
Soldatensender Calais
"Soldatensender Calais" operated on the mediumwave band on 833 kHz (360 metres), 714 kHz (420 metres), and 612 kHz (490 metres), with an associated shortwave station "Kurzwellensender Atlantik" created to broadcast to U-boat crews. The station used a 500 kilowatt transmitter originally built for American broadcaster WJZ, in Newark, New Jersey. This transmitter had lain unused at the factory after the United States Federal Communications Commission imposed a 50 kW power limit on all U.S. stations, and so RCA was glad to sell it overseas and the British Secret Service bought it for £165,000. Codenamed Aspidistra, it was installed in a huge, underground bunker near Crowborough in Sussex, England, where it was briefly the world's largest medium wave station, perfect for deceptive "black" operation.
Media of Ivory Coast
Stations of close proximity represent local interests and carry programming oriented towards community life, such as social, economic and cultural programs. These are located within a broadcasting area of 10 km. Since June 1998, stations began transmitting under a decree issued on September 13, 1995, that set down their rules of operation.
Land mobile radio system
Mobile and portable stations have a fairly limited range, usually three to twenty miles (~5 to 32 km) depending on terrain. Repeaters can be used to increase the range of these stations. They are usually placed upon hills and buildings to increase range.
X band
These three stations, located approximately 120 degrees apart in longitude, provide continual communications from the Earth to almost any point in the Solar System independent of Earth rotation. DSN stations are capable of using the older and lower S band deep-space radio communications allocations, and some higher frequencies on a more-or-less experimental basis, such as in the K band.
Radio broadcasting
AM radio transmitters can transmit audio frequencies up to 15 kHz (now limited to 10 kHz in the US due to FCC rules designed to reduce interference), but most receivers are only capable of reproducing frequencies up to 5 kHz or less. At the time that AM broadcasting began in the 1920s, this provided adequate fidelity for existing microphones, 78 rpm recordings, and loudspeakers. The fidelity of sound equipment subsequently improved considerably, but the receivers did not. Reducing the bandwidth of the receivers reduces the cost of manufacturing and makes them less prone to interference. AM stations are never assigned adjacent channels in the same service area. This prevents the sideband power generated by two stations from interfering with each other. Bob Carver created an AM stereo tuner employing notch filtering that demonstrated that an AM broadcast can meet or exceed the 15 kHz baseband bandwidth allotted to FM stations without objectionable interference. After several years, the tuner was discontinued. Bob Carver had left the company and the Carver Corporation later cut the number of models produced before discontinuing production completely.
Radio 390
Radio 390 was named after the station's wavelength, so listeners would know where to tune. The actual wavelength was 388 metres (773 kHz), but 390 was easier to remember. Like its neighbour, Radio City, Radio 390 took advantage of the fort's layout by erecting a 250-foot vertical mast on an inner tower, guyed to three of the outer towers. This, with additional elevation from the height of the towers, gave a stable and efficient antenna, better than ship-based stations, ensuring coverage of southern England with only a 10 kilowatt transmitter. For advertisers, the station claimed 35 kilowatts.
Line-of-sight propagation
However, at frequencies above 30 MHz (VHF and higher) and in lower levels of the atmosphere, neither of these effects are significant. Thus, any obstruction between the transmitting antenna (transmitter) and the receiving antenna (receiver) will block the signal, just like the light that the eye may sense. Therefore, since the ability to visually see a transmitting antenna (disregarding the limitations of the eye's resolution) roughly corresponds to the ability to receive a radio signal from it, the propagation characteristic at these frequencies is called "line-of-sight". The farthest possible point of propagation is referred to as the "radio horizon".
EXtreme Radio Service
The range of the eXRS radios is not explicitly stated, however, the manufacturer claims that it is equal to or greater than FRS and GMRS. Since the Earth is curved, the range of two way radios at these frequencies is limited to about 6 miles in good conditions, regardless of the advertised range.
Radio propagation
Several different types of propagation are used in practical radio transmission systems. Line-of-sight propagation means radio waves which travel in a straight line from the transmitting antenna to the receiving antenna. Line of sight transmission is used to medium range radio transmission such as cell phones, cordless phones, walkie-talkies, wireless networks, FM radio and television broadcasting and radar, and satellite communication, such as satellite television. Line-of-sight transmission on the surface of the Earth is limited to the distance to the visual horizon, which depends on the height of transmitting and receiving antennas. It is the only propagation method possible at microwave frequencies and above. At microwave frequencies, moisture in the atmosphere (rain fade) can degrade transmission.
Cell site
The "maximum" range of a mast (where it is not limited by interference with other masts nearby) depends on the same considerations.In any case the limiting factor is the ability of a low-powered personal cell phone to transmit back to the mast. As a rough guide, based on a tall mast and flat terrain, it may be possible to get between 50 and 70 km (30–45 miles). When the terrain is hilly, the maximum distance can vary from as little as to due to encroachment of intermediate objects into the wide center fresnel zone of the signal. Depending on terrain and other circumstances, a GSM Tower can replace between 2 and of cabling for fixed wireless networks. In addition, some technologies, such as GSM, have an additional absolute maximum range of , which is imposed by technical limitations. CDMA and IDEN have no such limit defined by timing.
The concept of "maximum" range is misleading, however, in a cellular network. Cellular networks are designed to support many conversations with a limited number of radio channels (slices of radio frequency spectrum necessary to make one conversation) that are licensed to an operator of a cellular service. To overcome this limitation, it is necessary to repeat and reuse the same channels at different locations. Just as a car radio changes from one local station to a completely different local station with the same frequency when you travel to another city, the same radio channel gets reused on a cell mast only a few miles away. To do this, the signal of a cell mast is intentionally kept at low power and in many cases tilted downward to limit its reach. This allows covering an area small enough not to have to support more conversations than the available channels can carry. Due to the sectorized arrangement of antennas on a tower, it is possible to vary the strength and angle for each sector depending on the coverage from other towers in the area.
PMR446
Range may be many kilometres, for example between hilltops, or only a few hundred metres, if for example a hill or large metal object is in the transmission path between radios. The best known long distance record is 333 mi (535.8 km) from Blyth in the United Kingdom to Almere, Netherlands. This was the result of enhanced propagation conditions, not a line-of-sight signal.
Satellite radio
Ground stations transmit signals to the satellites which are 35,786 kilometers (22,236 miles) above the Equator in Clarke belt orbits. The satellites send the signals back down to radio receivers in cars and homes. This signal contains scrambled broadcasts, along with meta data about each specific broadcast. The signals are unscrambled by the radio receiver modules, which display the broadcast information. In urban areas, ground repeaters enable signals to be available even if the satellite signal is blocked. The technology allows for nationwide broadcasting, so that, for instance US listeners can hear the same stations anywhere in the country.
FM broadcasting
This is still less than the range of AM radio waves, which because of their lower frequency can travel as ground waves or reflect off the ionosphere, so AM radio stations can be received at hundreds (sometimes thousands) of miles. This is a property of the carrier wave's typical frequency (and power), not its mode of modulation.
Title 47 CFR Part 15
Unlicensed broadcasts on the FM broadcast band (88 to 108 MHz) are limited to a field strength of 250 µV/m at a distance of 3 meters from the antenna. This is roughly equivalent to 0.01 microwatts. Emissions must be kept within the 88.0 to 108.0 MHz band under Part 15 rules.
Spectrum
In radio and telecommunications, the frequency spectrum can be shared among many different broadcasters. The radio spectrum is the part of the electromagnetic spectrum corresponding to frequencies lower below 300 GHz, which corresponds to wavelengths longer than about 1 mm. The microwave spectrum corresponds to frequencies between 300 MHz (0.3 GHz) and 300 GHz and wavelengths between one meter and one millimeter. Each broadcast radio and TV station transmits a wave on an assigned frequency range, called a "channel". When many broadcasters are present, the radio spectrum consists of the sum of all the individual channels, each carrying separate information, spread across a wide frequency spectrum. Any particular radio receiver will detect a single function of amplitude (voltage) vs. time. The radio then uses a tuned circuit or tuner to select a single channel or frequency band and demodulate or decode the information from that broadcaster. If we made a graph of the strength of each channel vs. the frequency of the tuner, it would be the frequency spectrum of the antenna signal.
Voice of the Strait
The radio's wave power is very large; waves mainly cover Taiwan and East China, Asia, Europe, Africa, Oceania and America, and even the Arctic and Antarctic can also receive shortwave broadcasts belonging to the international radio. While the Mediumwave of power is very small, in the daytime distance near the launch site, almost can not receive.
Radio broadcasting
Broadcasting by radio takes several forms. These include AM and FM stations. There are several subtypes, namely commercial broadcasting, non-commercial educational (NCE) public broadcasting and non-profit varieties as well as community radio, student-run campus radio stations, and hospital radio stations can be found throughout the world. Many stations broadcast on shortwave bands using AM technology that can be received over thousands of miles (especially at night). For example, the BBC, VOA, VOR, and Deutsche Welle have transmitted via shortwave to Africa and Asia. These broadcasts are very sensitive to atmospheric conditions and solar activity.
Radio spectrum
Radar applications use relatively high power pulse transmitters and sensitive receivers, so radar is operated on bands not used for other purposes. Most radar bands are in the microwave part of the spectrum, although certain important applications for meteorology make use of powerful transmitters in the UHF band.
Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies as high as 300 GHz to as low as 3 kHz, though some definitions describe waves above 1 or 3 GHz as microwaves, or include waves of any lower frequency. At 300 GHz, the corresponding wavelength is 1 mm (0.039 in), and at 3 kHz is 100 km (62 mi). Like all other electromagnetic waves, they travel at the speed of light. Naturally occurring radio waves are generated by lightning, or by astronomical objects.
FM broadcasting in the United States
Because each channel is 0.2 MHz wide, the center frequencies of adjacent channels differ by 0.2 MHz. Because the lowest channel is centered on 87.9 MHz, the tenths digit (in MHz) of the center frequency of any FM station in the United States is always an odd number. FM audio for analog television channel 6 is broadcast at a carrier frequency of 87.75 MHz, and many radios can tune this low; full-power stations ceased analog operations in 2009 under FCC orders, but a few low-power stations are still operated solely for their right to use this frequency and broadcast only nominal video programming, if any (these, too, will reportedly eventually be forced to shut down). For the same reason, assignment restrictions between TV stations on channel 6 and nearby FM stations are stringent: there are only two stations in the United States (KSFH, a 10-watt student station in Mountain View, California; and CSN International translator K200AA in Sun Valley, Nevada) licensed to operate on 87.9 MHz, both because they were forced off of other channels. Therefore, in effect, the FM broadcast band comprises only FM channels 201 (88.1 MHz) through 300 (107.9 MHz).
Radio Feltham
In November 2004, Radio Feltham celebrated its 10-year broadcasting milestone by switching its transmitters from 999AM to 87.8FM. The station, run by young prisoners aged 15 to 21, expanded its usual in-house broadcast to offer a community service of music, news and information to Feltham, to a potential audience of one million residents within a 10 mile radius of HMP Feltham.
AM broadcasting
The frequency ranges given here are those that are allocated to stations. Because of the bandwidth taken up by the sidebands, the range allocated for the band as a whole is usually about 5 kHz wider on either side.
"Longwave" (also known as Low frequency (LF)) (148.5–283.5 kHz) Broadcasting stations in this band are assigned transmitting frequencies in the range 153–279 kHz, and generally maintain 9 kHz spacing. 
Longwave assignments for broadcasting only exist in ITU Region 1 (Europe, Africa, and northern and central Asia), and is not allocated elsewhere. Individual stations have coverage measured in the hundreds of kilometers, however there are only a very limited number of available broadcasting slots.
Warsaw radio mast
After the collapse of the radio mast at Konstantynów, the Polish broadcasting company used the old Raszyn transmitter with its mast near Warsaw, which had been used since 1978 for daytime transmissions of a second Polish broadcasting service programme in the longwave range on the frequency AM-LW 198 kHz, for transmissions on AM-LW 225 kHz with a power of 500 kilowatts. It is not possible to transmit from Raszyn on AM-LW (long wave) 198 kHz/1515 meters and 225 kHz/1333 meters simultaneously, so the transmissions on the second longwave frequency AM-LW (long wave) 198 kHz had to be discontinued until either a second longwave broadcasting transmitting facility was built in Poland or a special frequency switch, which would allow transmissions on both frequencies, was installed at the Raszyn transmitter. The latter, simpler solution would have decreased the effectiveness and reliability of both transmitters and was therefore found unacceptable.
Manchester United Radio
The station was a Low Power AM station only available when Manchester United played a home game at Old Trafford, generally broadcasting from around three hours before kick-off until around two hours after the final whistle. As an LPAM station broadcasting with a Restricted Service Licence, it could only be received within a limited distance from the stadium – approximately a 50-mile radius.
List of 2.4 GHz radio use
Amateur Radio operators can transmit two-way Amateur television (and voice) in the 2.4 GHz band - and all ISM frequencies above 902 MHz - with maximum power of 1500 watts in the US if the transmission mode does not include spread spectrum techniques. Other power levels apply per regions. In the UK, the maximum power level for a full licence is 400 watts. In other countries, maximum power level for non - spread spectrum emissions are set by local legislation. 
Although the transmitter of some video cameras appears to be fixed on one frequency, it has been found in several models that the cameras are actually frequency agile, and can have their frequency changed by disassembling the product and moving solder links or dip switches inside the camera.
Broadcast range
Various broadcast relay stations can help to extend a station's area by retransmitting them on the same or another channel. What is usually called a repeater in amateur radio is called a broadcast translator (different channel) or booster (same channel) in American broadcasting, or the much broader category or rebroadcasters in Canadian broadcasting (which includes more than just the low-power broadcasting used in the U.S.) Boosters are used only within the broadcast range of the parent station, and serve the same function locally as regional and national single-frequency networks do in Europe. Distributed transmission has also undergone tests in the U.S., but to preserve stations' market share in their home media markets, these will be limited to the broadcast area of a single large station. Satellite radio, which is designed for use without a dish, also uses ground repeaters in large cities due to the many obstructions their high-rise buildings cause to the many current and potential customers that are concentrated there.
WHA (AM)
Initially there were no formal standards for stations providing a broadcast service, so there was no problem with 9XM broadcasting under an Experimental license. However, effective December 1, 1921, the Department of Commerce adopted regulations defining a broadcast service. The new regulations specified two transmitting wavelengths — 360 meters (833 kHz) for "entertainment", and 485 meters (619 kHz) for "market and weather reports" — and also required stations making broadcasts intended for the general public to hold a "Limited Commercial" license. Professor Terry filed an application for the new license, and on January 13, 1922 the University was issued its first broadcasting station authorization, with the randomly assigned call letters of WHA. In addition to the two broadcasting wavelengths, the station was authorized to use 410 meters (731 kHz) "for intercommunication between college stations".
All India Radio
The external services of AIR are also broadcast to Europe in DRM (Digital Radio Mondiale) on 9950 kHz between 1745–2230 UTC. These external transmissions are broadcast by high-power transmitters located at Aligarh, Bengaluru, Chennai, Delhi, Gorakhpur, Guwahati, Mumbai and Panaji on shortwave and from Jalandhar, Kolkata, Nagpur, Rajkot and Tuticorin on medium wave. Soon All India Radio Amritsar will also start a booster service on the FM band. Some of these transmitters are 1000 kW (1 MW) or 500 kW. Programs are beamed to different parts of the world except for the Americas and the reception quality is very good in the target areas. In each language service, the program consists of news, commentary, a press review, talks on matters of general or cultural interest, feature programmes, documentaries and music from India and the target region. Most programs originate at New Broadcasting House on Parliament Street in New Delhi, with a few originating at SPT Bengaluru, Chennai, Hyderabad, Jalandhar, Kolkata, HPT Malad Mumbai, Thiruvananthapuram and Tuticorin.
WWV (radio station)
As of May 1920 the Bureau's Radio Laboratory was reported to be conducting weekly Friday evening concerts from 8:30 to 11:00, transmitting on 600 kHz. That same month, the Bureau demonstrated a portable radio receiver, called the "portaphone", which was said to be capable of receiving broadcast programs for up to away. A newspaper article the following August reported that the weekly concerts could be heard up to from Washington. However, it also noted that "The bureau has been experimenting with the wireless music for several months, and has reached such an advanced stage of development that further investigation to them is useless, and they are going to discontinue the concerts."
KAUR
KAUR (89.1 FM) is a radio station broadcasting programming from Minnesota Public Radio's News & Information service. Licensed to Augustana University in Sioux Falls, South Dakota, United States, the station serves the greater Sioux Falls area and can reliably broadcast up to approximately 30 miles in any direction. The station is currently owned by Augustana University and operated by MPR.
Clarence D. Tuska
Under the provisions of the Radio Act of 1912, most amateur stations were restricted to operating on a wavelength of 200 meters (1500 kHz), which effectively limited their transmitting range to about 25 miles (40 kilometers). In the spring of 1914, Hiram Percy Maxim began promoting the idea of a national organization of amateurs that would transmit messages over greater distances by organizing relays. This resulted in Maxim's incorporation of the American Radio Relay League, with Maxim as president, and Tuska the organization's secretary. At this time Tuska also resigned from the Hartford Radio Club.
Association of Community Access Broadcasters
Access Manawatu broadcasts on 999 AM in Manawatu. It operates up to 13 hours each day, and includes many shows about groups, hobbies, interests, faiths and communities that are not represented in other media. Its 999 AM frequency reaches as far as Marton and Porewa in the north, Woodville and Pahiatua in the east, and Foxton and Shannon in the south. The station is owned by Manawatu Access Radio Charitable Trust and receives funding from Palmerston North City Council, Destination Manawatu and other funding bodies.
Radio propagation
At lower frequencies in the MF, LF, and VLF bands, due to diffraction radio waves can bend over obstacles like hills, and travel beyond the horizon as surface waves which follow the contour of the Earth. These are called ground waves. AM broadcasting stations use ground waves to cover their listening areas. As the frequency gets lower, the attenuation with distance decreases, so very low frequency (VLF) and extremely low frequency (ELF) ground waves can be used to communicate worldwide. VLF and ELF waves can penetrate significant distances through water and earth, and these frequencies are used for mine communication and military communication with submerged submarines.
KFC (defunct radio station)
Initially there were no formal standards for radio stations making broadcasts for the general public, and a variety of stations, most operating under Experimental or Amateur station licenses, conducted broadcasts on a regular schedule. On December 1, 1921 the U.S. Department of Commerce, which regulated radio at this time, adopted the first regulation formally establishing a broadcasting station category, which set aside the wavelength of 360 meters (833 kHz) for entertainment broadcasts, and 485 meters (619 kHz) for market and weather reports.
Longwave
Because of their long wavelength, radio waves in this frequency range can diffract over obstacles like mountain ranges and travel beyond the horizon, following the contour of the Earth. This mode of propagation, called "ground wave", is the main mode in the longwave band. The attenuation of signal strength with distance by absorption in the ground is lower than at higher frequencies, and falls with frequency. Low frequency ground waves can be received up to from the transmitting antenna. Very low frequency waves below 30 kHz can be used to communicate at transcontinental distances, and can penetrate saltwater to depths of hundreds of feet, and is used by the military to communicate with submerged submarines.
Longwave
In contemporary usage, the term "longwave" is not defined precisely, and its intended meaning varies. It may be used for radio wavelengths longer than 1,000 m i.e. frequencies up to 300 kilohertz (kHz), including the International Telecommunications Union's (ITU's) low frequency (LF, 30–300 kHz) and very low frequency (VLF, 3–30 kHz) bands. Sometimes the upper limit is taken to be higher than 300 kHz, but not above the start of the medium wave broadcast band at 525 kHz.
6-meter band
The Radio Regulations of the International Telecommunication Union allow amateur radio operations in the frequency range from 50.000 to 54.000 MHz in ITU Region 2 and 3. At ITU level, Region 1 is allocated to broadcasting. However, in practice a large number of ITU Region 1 countries allow amateur use of at least some of the 6-meter band. Over the years portions have been vacated by VHF television broadcasting channels for one reason or another. In November 2015 the ITU World Radio Conference (WRC-15) agreed that for their next conference in 2019, Agenda Item 1.1 will study a future allocation of 50–54 MHz to amateur radio in Region 1.
W250BC
It has a power of 250 watts but at great height, and is transmitted from a major broadcast tower near North Druid Hills along with several other FM and TV stations. It has a broadcast range of approximately , depending on how weather and other factors affect radio propagation conditions of other distant stations that can cause interference.
Radio propagation
At medium wave and shortwave frequencies (MF and HF bands) radio waves can refract from a layer of charged particles (ions) high in the atmosphere, called the ionosphere. This means that radio waves transmitted at an angle into the sky can be reflected back to Earth beyond the horizon, at great distances, even transcontinental distances. This is called skywave propagation. It is used by amateur radio operators to talk to other countries, and shortwave broadcasting stations that broadcast internationally. Skywave communication is variable, dependent on conditions in the upper atmosphere; it is most reliable at night and in the winter. Due to its unreliability, since the advent of communication satellites in the 1960s, many long range communication needs that previously used skywaves now use satellites.
FM broadcasting in the United States
High power is useful in penetrating buildings, diffracting around hills, and refracting for some distance beyond the horizon. 100,000-watt FM stations can regularly be heard up to 100 miles (160 km) away, and farther (e.g., 150 miles, 240 km) if there are no competing signals.
Radio Tonga
The most far-reaching of all Radio Tonga's services, this channel broadcasts daily from 6am to midnight, on a frequency of 1017 kHz. This is the only service of TBC that has been in operation since TBC's inception in 1961. It features local, Pacific & international news, as well as Tongan music, and overseas retro music, mostly from the 1970s & 1980s. Several local church organisations and businesses have weekly programs, and, though it is government-owned and funded, a significant source of its profit relies on in-house commercial advertising. In the event of local emergencies, such as tropical cyclones, Radio Tonga has been known to stay on the air all night with constant cyclone updates from the Tonga Meteorological Service. Radio Tonga 1 can be heard throughout the entire Kingdom of Tonga, including the outer island groups of Ha'apai, Vava'u, Niuafo'ou & Niuatoputapu, although there have been reports of listeners receiving the signal in other countries, such as Samoa and Finland. The station broadcasts with a power output of 10,000 Watts into a non directional antenna.
Formerly known as FM97, now broadcasting on a frequency of 90.0 MHz, this commercial FM station commenced in the early 1990s, and now runs 24 hours a day, playing mostly chart-toppers from abroad. After the local broadcast ends at midnight, BBC programming is relayed live via satellite until the local broadcast resumes at 6am. This service can only be heard on the main island of Tongatapu, and its closely surrounding islands such as 'Eua, Pangaimotu and Atata. The station broadcasts with 500 watts.
Cell Broadcast
Cell Broadcast is a mobile technology that allows messages (up to 1395 characters) to be broadcast to all mobile handsets and similar devices within a designated geographical area (polygon). The broadcast range can be varied, from a single cell to the entire network.
U.S. Naval Radio Station, Tarlac
The station comprised 1,937 acres. The core of its transmission capability was located in two transmitter buildings. The primary building, referred to as "Main Deck", housed a large number of high power, high frequency (HF) transmitters. It also housed microwave radio-relay equipment for reception and distribution of data received from the NavComStaPhil for subsequent short-wave radio transmission. The secondary transmitter building, referred to as "Bull Horn", housed a smaller number of transmitters, but with similar capabilities to those at Main Deck. Additionally, the Bull Horn site held the S-500 transmitter trailer. The S-500, known affectionately as "Big Sam", was a high power, low frequency (LF) transmitter dedicated for fleet broadcast, capable of generating 500 kW of broadcast signal power. Radio transmitters employed at both sites were in the category of high-power output, meaning, they generated radio signal powers in the range from a few kilowatts (kW) to several 10's of kW, but the majority of transmitters operated at either 10 kW or 40 kW. A large number and variety of LF and HF antennas were used at both transmitter sites. These included directional (beam antennas), omnidirectional antennas, and tall antenna towers for dedicated, wide-area broadcast capability.
An extensive infrastructure supported the station. This included a multi-purpose building with barracks, administration offices, mess hall, navy exchange, and recreation room; an enlisted men's club, autonomous power generating facility, water and sewer treatment facilities, helicopter pad, and security posts. Eventually, a swimming pool and tennis court were added.
Raszyn radio transmitter
The longwave transmitter Raszyn was until the inauguration of Warsaw radio mast in Konstantynów the central longwave broadcasting of Poland.
Since 1978 from this facility during daytime a second program in the longwave range was transmitted on AM-LW (long wave)198 kHz/1515 meters (formerly the frequency was used by Radio Parlament).
After the collapse of Warsaw radio mast in 1991 this facility was used until the inauguration of the new longwave-transmitter Solec Kujawski for transmissions of the first program of the Polish Broadcasting Service on AM-LW (longwave) 225 kHz/1333 meters. Because it was not possible to transmit from Raszyn on both longwave frequencies of the Polish Broadcasting Company simultaneously, no transmissions on the second longwave frequency of the Polish Broadcasting Company (AM-LW 198 kHz/1515 meters) took place between 1991 and 1999.
The radio mast of the longwave transmitter Raszyn is since the collapse of the Warsaw radio mast the sixth tallest structure in Poland. On July 31, 2009 Polish Radio Parlament on has discontinued their broadcast on AM-LW (longwave) due to economical crisis, and the longwave transmitter has been turned off.
Microwave transmission
The next higher part of the radio electromagnetic spectrum, where the frequencies are above 30 GHz and below 100 GHz, are called "millimeter waves" because their wavelengths are conveniently measured in millimeters, and their wavelengths range from 10 mm down to 3.0 mm (Higher frequency waves are smaller in wavelength). Radio waves in this band are usually strongly attenuated by the Earthly atmosphere and particles contained in it, especially during wet weather. Also, in a wide band of frequencies around 60 GHz, the radio waves are strongly attenuated by molecular oxygen in the atmosphere. The electronic technologies needed in the millimeter wave band are also much more difficult to utilize than those of the microwave band.Microwave radio relay is a technology widely used in the 1950s and 1960s for transmitting signals, such as long-distance telephone calls and television programs between two terrestrial points on a narrow beam of microwaves. In microwave radio relay, microwaves are transmitted on a line of sight path between relay stations using directional antennas, forming a fixed radio connection between the two points. The requirement of a line of sight limits the separation between stations to the visual horizon, about 30 to 50 miles. Before the widespread use of communications satellites, chains of microwave relay stations were used to transmit telecommunication signals over transcontinental distances.
General Order 40
Radio transmissions in the United States were originally regulated by the Department of Commerce, as authorized by the Radio Act of 1912. The first formal regulations governing broadcasts intended for the general public were adopted effective December 1, 1921. This initially established just two transmitting wavelengths — 360 meters (833 kHz) for "entertainment" broadcasts, and 485 meters (619 kHz) for "market news and weather reports".. The number of broadcasting stations grew dramatically in 1922, reaching over 500 by the end of the year, and the government began making available additional frequencies. By November 1924 a band of frequencies, from 550 to 1500 kHz, had been established, with higher-powered stations, known as "Class B", assigned to the frequencies from 550 to 1070, while lower-powered "Class A" stations were assigned to 1080 to 1500.
Personal radio service
FRS (規範頻率), 14 channels, 12.5 kHz spacing:Since 3 February 2004, the Infocomm Development Authority of Singapore (IDA) has allocated the 446.0–446.1 MHz frequency band for low-powered walkie-talkies on a non-interference, non-protected and shared-use basis. As these walkie-talkies are low-powered devices which do not potentially cause interference to other licensed radio services, it need not be licensed for use in Singapore. However, the device must be type approved by IDA for local sale.
Citizens Band radio is a family of services available in different countries and with different operating rules, generally using channels in the 27 MHz part of the radio spectrum. 26–27 MHz occupies the "boundary area" between HF (3–30 MHz) and VHF (30–300 MHz). This means that CB signals provide local coverage similar to low-band VHF during times of low sunspot activity. However, during the peak of the sunspot cycle, CB frequencies exhibit skywave propagation just like the lower parts of HF do, making communication hundreds or even thousands of miles (km) away possible. While some operators seek out long distance "DX" contacts on CB frequencies and on frequencies above channel 40 and below channel 1 (a practice referred to as "freebanding" or "outbanding"), interference from distant stations will often make local communication extremely difficult or impossible during band openings. CB was, and still is, designed for short-distance (local) communications needs. US FCC law prohibits communicating with any station more than 250 km (155.3 miles) on CB frequencies.(150 mile rule deleted by FCC September -2017) Like many rules regarding the HF CB services, the distance prohibition is largely ignored and unenforced. Often as a result of channel overcrowding and interference, many HF CB users have turned to purchasing "export" or "10-meter" radios that operate in the legal CB band but also provide access to frequencies above and below the CB band. Other CB users purchase amplifiers to increase their output power and "punch through" interference caused by distant stations (or by local stations running amplifiers). This has created a tragedy of the commons situation in and near the HF CB spectrum (25–28 MHz). As more users purchase amplifiers and operate on out-of-band frequencies, more interference is produced, forcing others to acquire even more powerful equipment to punch through even more interference, and/or to acquire transceivers capable of accessing more frequencies so that a clear frequency may be found. Many CB users have moved to other personal radio services to avoid these issues.
WXDU
Getting an FM station on the air is no trivial task: among other things, WDUK would need a large amount of funding, University support, an FCC license, and a place to put the transmitter. The decision on where to put the transmitter was pivotal. Due to nearby stations of 88.5 and 88.9, a new station on 88.7 would not be able to operate at a very high power level. If the transmitter were put on campus, it could operate at a couple of hundred watts of power, and could reach almost a hundred square miles. If the transmitter were put at a location in the Duke Forest in Hillsborough, NC, it could operate at over one thousand watts, and could reach over three hundred square miles. The latter option would be a gamble, however, as studies showed that reception on campus could turn out to be marginal.
Radio y Televisión Martí
Today, Radio Marti broadcasts a 24-hour radio program over short-wave transmitters in Delano, California, and Greenville, North Carolina, and a medium-wave transmitter in Marathon, Florida (GC: ). Its studios are located in Miami, Florida. Cuba jams both the medium-wave and shortwave signals, but the shortwave program is heard in Canada and throughout Central America and South America. On occasion, the medium-wave transmitter at 1180 kHz can be heard as far north as Washington, D.C.
Radio telescope
The above stationary dishes are not fully "steerable"; they can only be aimed at points in an area of the sky near the zenith, and cannot receive from sources near the horizon. The largest fully steerable dish radio telescope is the 100 meter Green Bank Telescope in West Virginia, United States, constructed in 2000. The largest fully steerable radio telescope in Europe is the Effelsberg 100-m Radio Telescope near Bonn, Germany, operated by the Max Planck Institute for Radio Astronomy, which also was the world's largest fully steerable telescope for 30 years until the Green Bank antenna was constructed. The third-largest fully steerable radio telescope is the 76-meter Lovell Telescope at Jodrell Bank Observatory in Cheshire, England, completed in 1957. The fourth-largest fully steerable radio telescopes are six 70-meter dishes: three Russian RT-70, and three in the NASA Deep Space Network. , the planned Qitai Radio Telescope will be the world's largest fully steerable single-dish radio telescope with a diameter of .
General Mobile Radio Service
As with other UHF radio services, reliable range is considered to be line-of-sight and the distance to the radio horizon can be estimated based on antenna height. Theoretically, the range between two hand-held units would be about one or two miles (about 1.5–3 km); mobile units have higher antennas and a range of around 5 miles (8 km). A GMRS repeater with an antenna that is high above the surrounding terrain can extend the usable range over a wide area – for example, up to a 20 mile (32.2 km) radius around the repeater station. Obstructions such as hills and buildings can reduce range. Higher power does not necessarily give a proportional increase in range, although it may improve the reliability of communication at the limits of line-of-sight distance.
Radio frequency
Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around twenty thousand times per second () to around three hundred billion times per second (). This is roughly between the upper limit of audio frequencies and the lower limit of infrared frequencies; these are the frequencies at which energy from an oscillating current can radiate off a conductor into space as radio waves. Different sources specify different upper and lower bounds for the frequency range. While RF usually refers to electrical rather than mechanical oscillations, mechanical RF systems are not uncommon (see mechanical filter and RF MEMS).
AM broadcasting
Some microbroadcasters, especially those in the United States operating under the FCC's Part 15 rules, and pirate radio operators on mediumwave and shortwave, achieve greater range than possible on the FM band. On mediumwave these stations often transmit on 1610 kHz to 1710 kHz. Hobbyists also use low-power AM (LPAM) transmitters to provide programming for vintage radio equipment in areas where AM programming is not widely available or does not carry programming the listener desires; in such cases the transmitter, which is designed to cover only the immediate property and perhaps nearby areas, is connected to a computer, an FM radio or an MP3 player. Microbroadcasting and pirate radio have generally been supplanted by streaming audio on the Internet, but some schools and hobbyists still use LPAM transmissions.
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.
Skywave
As a result of skywave propagation, a signal from a distant AM broadcasting station, a shortwave station, or – during sporadic E propagation conditions (principally during the summer months in both hemispheres) a distant VHF FM or TV station – can sometimes be received as clearly as local stations. Most long-distance shortwave (high frequency) radio communication – between 3 and 30 MHz – is a result of skywave propagation. Since the early 1920s amateur radio operators (or "hams"), limited to lower transmitter power than broadcast stations, have taken advantage of skywave for long distance (or "DX") communication.
Project Sanguine
Radio waves in the extremely low frequency (ELF) band of 30 to 300 Hz can penetrate to a depth of hundreds of meters, allowing them to communicate with submarines at their normal operating depth. The lower the frequency, the longer the wavelength of the radio waves, and transmitters require longer antenna structures to generate them. ELF transmitters use huge antennas called ground dipoles consisting of tens to hundreds of kilometers of overhead cables resembling ordinary power transmission lines. The transmission lines are grounded at the ends, and looping currents deep in the Earth form part of the antenna. Because even these huge antennas are much smaller than the ELF wavelengths, they are extremely inefficient; only a tiny fraction of the input power is radiated as ELF waves, with the rest dissipated as heat in antenna resistance. At their full input power of 2.6 MW, both US ELF transmitters working together only generated about 8 watts of ELF radiation. This weak signal was able to reach submarines over half the globe only because of the extremely low attenuation of ELF waves of 1–2 dB per 1000 kilometers. ELF transmitters are most efficient when sited over certain low conductivity underground rock formations, which forces the currents to spread deeper through a larger volume of rock, forming a larger "antenna". The US system was located in Wisconsin and the Upper Peninsula of Michigan over the Laurentian Shield formation, for that reason.
Dnyanvani
It is fondly called DY Radio by the students and locale of the community. It has a broadcast range of about 12–15 km(aerially) extending from Airoli to Panvel (the two extreme end of Navi Mumbai).
Radio wave
Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies as high as 300 gigahertz (GHz) to as low as 30 hertz (Hz). At 300 GHz, the corresponding wavelength is 1 mm, and at 30 Hz is 10,000 km. Like all other electromagnetic waves, radio waves travel at the speed of light. They are generated by electric charges undergoing acceleration, such as time varying electric currents. Naturally occurring radio waves are emitted by lightning and astronomical objects.
Height above ground level
In broadcasting, altitude AGL has relatively little direct bearing on the broadcast range of a station. Rather, it is HAAT (the height above the average terrain (in the surrounding area)) which is used to determine how far a broadcast station (or any other sort of VHF or higher radio-frequency) transmission will travel.
Felixstowe
Radio Caroline ship MV "Caroline" was outside the three-mile limit at Easter 1964. It was the very first UK radio station aboard a ship in the North Sea, and intended to break the monopoly of the BBC. Radio Caroline had about seven million listeners in its first week on air. The station's slogan was "Your all-day music station", and it initially broadcast from 6am to 6pm, seven days a week. The transmitter had a power of 10 kW on 199 metres – 1.520 kHz. The ship moved to waters off the Isle Of Man in summer 1965 to become Radio Caroline North, while MV "Mi-Amigo" of Radio Atlanta on 201 metres became Radio Caroline South, broadcasting on first 199 later on 259 metres – 1.178 kHz with 50 kW of power on medium wave. Later the ship moved to waters off Clacton-On-Sea, Essex.
Radio Caroline
Radio Caroline announced a wavelength of 199 metres, rhyming with the name, but was actually broadcasting on 197.3 metres (1520 kHz). Stations in the UK announced the wavelength in metres, and radios at that time were tuned using an analogue dial. The absence of precise digital readouts allowed for some leeway between the precise transmission frequency and the channel announced on the air. The Dutch offshore station Radio Veronica was on 192 metres (1562 kHz) and Radio Atlanta broadcast on 201 (1493 kHz).
Radio Newyork International
Eventually Allan Weiner did secure a shortwave broadcasting license of his own and today "Radio Newyork International" is one of many programs heard on Sunday evenings over WBCQ located in Monticello, Maine, USA.Appellants respectfully submit that this ruling creates a dangerous precedent in that it allows the government potentially to reach out and control broadcasters anywhere in the world as long as their broadcasts are able to be picked up somewhere within the borders of the United States. Does the FCC thus have power to shut down all broadcasts from the Caroline, a broadcast vessel moored in the North Sea, based upon a claim that signals from that vessel's radio broadcasts were picked up, however briefly and even if creating no interference, somewhere in this country?
KFC (defunct radio station)
The newspaper enlisted a local radio expert, Roscoe W. Bell of the Northern Radio Company, to set up a radio transmitter at the newspaper building. Arrangements were also made for the local Navy radio station, located at the L. C. Smith building, to participate by sending fight summaries via radiotelegraph, which had a much greater coverage than the radiotelephone station, although limited to listeners able to read Morse code dots-and-dashes. The reported wavelength to be used for a July 1 radiotelephone test transmission was 340 meters (882 kHz). The next day the newspaper reported that the test went well, so, beginning at 11:00 a.m., the radiotelephone broadcast would be sent on 275 meters (1091 kHz), while the Navy's radiotelegraph reports would go out on 600 meters (500 kHz).
Ultra high frequency
Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter (one decimeter). Radio waves with frequencies above the UHF band fall into the super-high frequency (SHF) or microwave frequency range. Lower frequency signals fall into the VHF (very high frequency) or lower bands. UHF radio waves propagate mainly by line of sight; they are blocked by hills and large buildings although the transmission through building walls is strong enough for indoor reception. They are used for television broadcasting, cell phones, satellite communication including GPS, personal radio services including Wi-Fi and Bluetooth, walkie-talkies, cordless phones, and numerous other applications.
Valley Public Radio
Despite having no translators, the two stations' combined signal covers most of California's San Joaquin Valley, including the cities of Fresno, Bakersfield, Visalia, Madera, Tulare, Clovis, Merced, and Hanford; however, much of this area gets only grade B coverage. KPRX operates with its maximum allowed U.S. Federal Communications Commission power (11,000 watts) for a Class B1 station with an antenna height of 152 meters; likewise KVPR broadcasts with its maximum allowed power (2,450 watts) and an antenna height of 576 meters for a Class B FM station. In FM broadcasting effective radiated power is inversely proportional to antenna height.
Reference distance
This is in turn used to define most broadcast classes for FM stations in North America. Each class (except D) is defined as having a maximum ERP and HAAT. If the HAAT of a station's radio antenna exceeds that specified for the class, it must reduce ERP so that its signal does not exceed the reference distance. The signal strength used differs by class, but generally the value is 1.0mV/m (millivolt per meter) or 60dBu (decibels over one microvolt per meter) for most of the United States, and 0.5mV/m or 54dBu in Canada, and for some U.S. stations in parts of certain areas including California, the Great Lakes region, and the Northeast. This is considered the service contour of a station by the Federal Communications Commission (FCC) and the Canadian Radio-television and Telecommunications Commission (CRTC), and by COFETEL in Mexico, according to NARBA and other international agreements among the three. The reference distances are in turn used to create mandatory minimum spacing distances among co-channel stations, and certain adjacent channels as well.
87.5 FM
87.5 FM is the first radio broadcast frequency that can be used on the FM band 87.5-108 or VHF Band 2. The use of 87.5 FM as the main carrier frequency of a legal radio station itself is rare in most countries as it transmits signals slightly out of band down to roughly 87.3 and possibly as low as 87.2 close to the transmitter.
2200-meter band
The 2200 meter or 136 kHz band is the lowest frequency band in which amateur radio operators are allowed to transmit. It was formally allocated to amateurs at the 2007 World Radiocommunication Conference (WRC-07). The band is available on a secondary basis in all ITU regions with the limitation that amateur stations have maximum radiated power of 1 Watt effective isotropic radiated power.
TV and FM DX
In February 1942, the first known published long-distance FM broadcast station reception report was reported by "FM magazine". The report provided details of 45.1 MHz W51C Chicago, Illinois, received in Monterrey, Mexico: "Zenith Radio Corporation, operating W51C, has received a letter from a listener in Monterrey, Mexico, telling of daily reception of this station between 3:00 P.M. and 6:00 P.M. This is the greatest distance, 1,100 miles, from which consistent reception of the 50 [kW] transmitter has been reported."
Reference distance
Real-world calculations can also be done by including data from digital topographical maps, typically along 12 or 16 radials, and including the specifications from the radiation pattern for a directional antenna. However, this does not fit the definition of a reference in this sense, even though it determines the actual broadcast range of a station. This actual range is used in the reserved band in the U.S., while the reference distance is used for commercial radio stations.
WSLQ
WSLQ has one of the largest coverage areas of all FM radio stations in the United States. Its effective radiated power (ERP) is 200,000 watts, broadcasting from a tower at 1962 feet in height above average terrain (HAAT). The Class C signal can be heard into West Virginia and North Carolina, and at times is picked up more than 200 miles away. The station was established in 1947, grandfathered at unusually high wattage before current Federal Communications Commission rules on FM power were set. Today, most FM stations are limited to 100,000 watts.
SATEL
The operation range of a radio modem varies depending on the transmission power, antenna gain and mast height, and environment. In rural areas a 1 W radio modem with a line-of-sight radio link may range over 20 km and even up to 50 km in exceptionally amicable environments. In dense metropolitan areas, a corresponding range may vary from several kilometers to over 10 km. With a 10 W radio modem, a range of up to 80 km can be reached in favorable environments. By using radio modem repeaters, much broader areas can be covered.