72-481: Intelsat Americas , was the re-designation given to the several Telstar satellites serving North America following their sale to Intelsat by Loral Space & Communications in 2003. On February 1, 2007, they were renamed under the "Galaxy" brand. The Telstar satellites that do not directly serve the United States retained their original Telstar designation. The following name conversions were applied to
144-647: A band being used for Milstar . Global Navigation Satellite Systems (GNSS) including the Chinese Beidou , the American Global Positioning System (introduced in 1978) and the Russian GLONASS broadcast navigational signals in various bands between about 1.2 GHz and 1.6 GHz. Radar is a radiolocation technique in which a beam of radio waves emitted by a transmitter bounces off an object and returns to
216-516: A standing wave is present, they may also be used to measure the distance between the nodes , which is equal to half the wavelength. The precision of this method is limited by the determination of the nodal locations. Microwaves are non-ionizing radiation, which means that microwave photons do not contain sufficient energy to ionize molecules or break chemical bonds, or cause DNA damage, as ionizing radiation such as x-rays or ultraviolet can. The word "radiation" refers to energy radiating from
288-458: A . Microwaves travel solely by line-of-sight paths; unlike lower frequency radio waves, they do not travel as ground waves which follow the contour of the Earth, or reflect off the ionosphere ( skywaves ). Although at the low end of the band they can pass through building walls enough for useful reception, usually rights of way cleared to the first Fresnel zone are required. Therefore, on
360-692: A H2A204 variant of the H-IIA rocket, and it commenced service in December 2015. Telstar 19V was launched on 22 July 2018. Telstar 18V was launched on 10 September 2018, on a SpaceX Falcon 9 . Microwave Microwave is a form of electromagnetic radiation with wavelengths shorter than other radio waves but longer than infrared waves. Its wavelength ranges from about one meter to one millimeter, corresponding to frequencies between 300 MHz and 300 GHz, broadly construed. A more common definition in radio-frequency engineering
432-431: A computer-controlled array of antennas that produces a beam that can be electronically steered in different directions. At microwave frequencies, the transmission lines which are used to carry lower frequency radio waves to and from antennas, such as coaxial cable and parallel wire lines , have excessive power losses, so when low attenuation is required, microwaves are carried by metal pipes called waveguides . Due to
504-535: A frequency near 2.45 GHz (12 cm) through food, causing dielectric heating primarily by absorption of the energy in water. Microwave ovens became common kitchen appliances in Western countries in the late 1970s, following the development of less expensive cavity magnetrons . Water in the liquid state possesses many molecular interactions that broaden the absorption peak. In the vapor phase, isolated water molecules absorb at around 22 GHz, almost ten times
576-422: A harmonic generator and a mixer. The accuracy of the measurement is limited by the accuracy and stability of the reference source. Mechanical methods require a tunable resonator such as an absorption wavemeter , which has a known relation between a physical dimension and frequency. In a laboratory setting, Lecher lines can be used to directly measure the wavelength on a transmission line made of parallel wires,
648-479: A large horizontal conical horn antenna with a parabolic reflector at its mouth that re-directed the beam. This particular design had very low sidelobes , and thus made very low receiving system noise temperatures possible. The aperture of the antennas was 3,600 sq ft (330 m ). The antennas were 177 ft (54 m) long and weighed 380 short tons (340,000 kg). Morimi Iwama and Jan Norton of Bell Laboratories were in charge of designing and building
720-530: A place in the electromagnetic spectrum with frequency above ordinary radio waves , and below infrared light: In descriptions of the electromagnetic spectrum , some sources classify microwaves as radio waves, a subset of the radio wave band, while others classify microwaves and radio waves as distinct types of radiation. This is an arbitrary distinction. Bands of frequencies in the microwave spectrum are designated by letters. Unfortunately, there are several incompatible band designation systems, and even within
792-515: A receiver, allowing the location, range, speed, and other characteristics of the object to be determined. The short wavelength of microwaves causes large reflections from objects the size of motor vehicles, ships and aircraft. Also, at these wavelengths, the high gain antennas such as parabolic antennas which are required to produce the narrow beamwidths needed to accurately locate objects are conveniently small, allowing them to be rapidly turned to scan for objects. Therefore, microwave frequencies are
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#1732787271546864-434: A single television channel, or multiplexed telephone circuits. Since the spacecraft spun, it required an array of antennas around its "equator" for uninterrupted microwave communication with Earth. An omnidirectional array of small cavity antenna elements around the satellite's "equator" received 6 GHz microwave signals to relay back to ground stations. The transponder converted the frequency to 4 GHz, amplified
936-449: A source and not to radioactivity . The main effect of absorption of microwaves is to heat materials; the electromagnetic fields cause polar molecules to vibrate. It has not been shown conclusively that microwaves (or other non-ionizing electromagnetic radiation) have significant adverse biological effects at low levels. Some, but not all, studies suggest that long-term exposure may have a carcinogenic effect. During World War II , it
1008-574: A system the frequency ranges corresponding to some of the letters vary somewhat between different application fields. The letter system had its origin in World War 2 in a top-secret U.S. classification of bands used in radar sets; this is the origin of the oldest letter system, the IEEE radar bands. One set of microwave frequency bands designations by the Radio Society of Great Britain (RSGB),
1080-474: A transistor failure, this time irreparably, and Telstar 1 went back out of service on February 21, 1963. Experiments continued, and by 1964, two Telstars, two Relay units (from RCA ), and two Syncom units (from the Hughes Aircraft Company ) had operated successfully in space. Syncom 2 was the first geosynchronous satellite and its successor, Syncom 3 , broadcast pictures from
1152-492: A vacuum under the influence of controlling electric or magnetic fields, and include the magnetron (used in microwave ovens ), klystron , traveling-wave tube (TWT), and gyrotron . These devices work in the density modulated mode, rather than the current modulated mode. This means that they work on the basis of clumps of electrons flying ballistically through them, rather than using a continuous stream of electrons. Low-power microwave sources use solid-state devices such as
1224-566: 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 remote broadcasting of news or sports events as the backhaul link 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). Most satellite communications systems operate in
1296-416: Is also used to perform rotational spectroscopy and can be combined with electrochemistry as in microwave enhanced electrochemistry . Microwave frequency can be measured by either electronic or mechanical techniques. Frequency counters or high frequency heterodyne systems can be used. Here the unknown frequency is compared with harmonics of a known lower frequency by use of a low-frequency generator,
1368-555: Is inversely proportional to the transmitted frequency. Microwaves are used in spacecraft communication, and much of the world's data, TV, and telephone communications are transmitted long distances by microwaves between ground stations and communications satellites . Microwaves are also employed in microwave ovens and in radar technology. Before the advent of fiber-optic transmission, most long-distance telephone calls were carried via networks of microwave radio relay links run by carriers such as AT&T Long Lines . Starting in
1440-424: Is limited to a few kilometers. A spectral band structure causes absorption peaks at specific frequencies (see graph at right). Above 100 GHz, the absorption of electromagnetic radiation by Earth's atmosphere is so effective that it is in effect opaque , until the atmosphere becomes transparent again in the so-called infrared and optical window frequency ranges. In a microwave beam directed at an angle into
1512-415: Is roughly spherical, measures 34.5 inches (880 mm) in length, and weighs about 170 lb (77 kg). Its dimensions were limited by what would fit on one of NASA's Delta rockets . Telstar was spin-stabilized , and its outer surface was covered with solar cells capable of generating 14 watts of electrical power. The original Telstar had a single innovative transponder that could relay data,
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#17327872715461584-432: Is tabulated below: Other definitions exist. The term P band is sometimes used for UHF frequencies below the L band but is now obsolete per IEEE Std 521. When radars were first developed at K band during World War 2, it was not known that there was a nearby absorption band (due to water vapor and oxygen in the atmosphere). To avoid this problem, the original K band was split into a lower band, K u , and upper band, K
1656-617: Is the range between 1 and 100 GHz (wavelengths between 30 cm and 3 mm), or between 1 and 3000 GHz (30 cm and 0.1 mm). The prefix micro- in microwave is not meant to suggest a wavelength in the micrometer range; rather, it indicates that microwaves are small (having shorter wavelengths), compared to the radio waves used in prior radio technology . The boundaries between far infrared , terahertz radiation , microwaves, and ultra-high-frequency (UHF) are fairly arbitrary and are used variously between different fields of study. In all cases, microwaves include
1728-672: The 1964 Summer Olympics in Tokyo. The first commercial geosynchronous satellite was Intelsat I ("Early Bird") launched in 1965. Telstar was considered a technical success. According to a US. Information Agency (USIA) poll, Telstar was better known in Great Britain than Sputnik had been in 1957. Subsequent Telstar satellites were advanced commercial geosynchronous spacecraft that share only their name with Telstar 1 and 2. The second wave of Telstar satellites launched with Telstar 301 in 1983, followed by Telstar 302 in 1984 (which
1800-616: The Big Bang , and is one of the few sources of information about conditions in the early universe. Due to the expansion and thus cooling of the Universe, the originally high-energy radiation has been shifted into the microwave region of the radio spectrum. Sufficiently sensitive radio telescopes can detect the CMBR as a faint signal that is not associated with any star, galaxy, or other object. A microwave oven passes microwave radiation at
1872-757: The direction générale des Télécommunications (France) to develop experimental satellite communications over the Atlantic Ocean. Bell Labs held a contract with NASA, paying the agency for each launch, independent of success. Six ground stations were built to communicate with Telstar, one each in the US, France, the UK, Canada, West Germany and Italy. The American ground station—built by Bell Labs—was Andover Earth Station , in Andover, Maine. The main British ground station
1944-577: The field-effect transistor (at least at lower frequencies), tunnel diodes , Gunn diodes , and IMPATT diodes . Low-power sources are available as benchtop instruments, rackmount instruments, embeddable modules and in card-level formats. A maser is a solid-state device which amplifies microwaves using similar principles to the laser , which amplifies higher frequency light waves. All warm objects emit low level microwave black-body radiation , depending on their temperature , so in meteorology and remote sensing , microwave radiometers are used to measure
2016-438: The 2.3 GHz, 2.5 GHz, 3.5 GHz and 5.8 GHz ranges. Mobile Broadband Wireless Access (MBWA) protocols based on standards specifications such as IEEE 802.20 or ATIS/ANSI HC-SDMA (such as iBurst ) operate between 1.6 and 2.3 GHz to give mobility and in-building penetration characteristics similar to mobile phones but with vastly greater spectral efficiency. Some mobile phone networks, like GSM , use
2088-401: The 30 minutes in each 2.5-hour orbit when the satellite passed over the Atlantic Ocean. Ground antennas had to track the satellite with a pointing error of less than 0.06 degrees as it moved across the sky at up to 1.5 degrees per second. Since the transmitters and receivers on Telstar were not powerful, ground antennas had to be 90 ft (27 m) tall. Bell Laboratory engineers designed
2160-425: The 5 GHz range. Licensed long-range (up to about 25 km) Wireless Internet Access services have been used for almost a decade in many countries in the 3.5–4.0 GHz range. The FCC recently carved out spectrum for carriers that wish to offer services in this range in the U.S. — with emphasis on 3.65 GHz. Dozens of service providers across the country are securing or have already received licenses from
2232-689: The 95 GHz focused beam heats the skin to a temperature of 54 °C (129 °F) at a depth of 0.4 millimetres ( 1 ⁄ 64 in). The United States Air Force and Marines are currently using this type of active denial system in fixed installations. Microwave radiation is used in electron paramagnetic resonance (EPR or ESR) spectroscopy, typically in the X-band region (~9 GHz) in conjunction typically with magnetic fields of 0.3 T. This technique provides information on unpaired electrons in chemical systems, such as free radicals or transition metal ions such as Cu(II). Microwave radiation
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2304-437: The C, X, K a , or K u bands of the microwave spectrum. These frequencies allow large bandwidth while avoiding the crowded UHF frequencies and staying below the atmospheric absorption of EHF frequencies. Satellite TV either operates in the C band for the traditional large dish fixed satellite service or K u band for direct-broadcast satellite . Military communications run primarily over X or K u -band links, with K
2376-623: The Earth's Van Allen Belt where Telstar 1 went into orbit. This vast increase in a radiation belt , combined with subsequent high-altitude blasts, including a Soviet test in October , overwhelmed Telstar's fragile transistors. It went out of service in November 1962, after handling over 400 telephone, telegraph , facsimile , and television transmissions. It was restarted by a workaround in early January 1963. The additional radiation associated with its return to full sunlight once again caused
2448-457: The FCC to operate in this band. The WIMAX service offerings that can be carried on the 3.65 GHz band will give business customers another option for connectivity. Metropolitan area network (MAN) protocols, such as WiMAX (Worldwide Interoperability for Microwave Access) are based on standards such as IEEE 802.16 , designed to operate between 2 and 11 GHz. Commercial implementations are in
2520-551: The Telstar satellites serving the United States: This spacecraft or satellite related article is a stub . You can help Misplaced Pages by expanding it . Telstar Telstar is the name of various communications satellites . The first two Telstar satellites were experimental and nearly identical. Telstar 1 launched on top of a Thor-Delta rocket on July 10, 1962. It successfully relayed through space
2592-490: The body. The lens and cornea of the eye are especially vulnerable because they contain no blood vessels that can carry away heat. Exposure to microwave radiation can produce cataracts by this mechanism, because the microwave heating denatures proteins in the crystalline lens of the eye (in the same way that heat turns egg whites white and opaque). Exposure to heavy doses of microwave radiation (as from an oven that has been tampered with to allow operation even with
2664-508: The door open) can produce heat damage in other tissues as well, up to and including serious burns that may not be immediately evident because of the tendency for microwaves to heat deeper tissues with higher moisture content. Microwaves were first generated in the 1890s in some of the earliest radio wave experiments by physicists who thought of them as a form of "invisible light". James Clerk Maxwell in his 1873 theory of electromagnetism , now called Maxwell's equations , had predicted that
2736-516: The early 1950s, frequency-division multiplexing was used to send up to 5,400 telephone channels on each microwave radio channel, with as many as ten radio channels combined into one antenna for the hop to the next site, up to 70 km away. Wireless LAN protocols , such as Bluetooth and the IEEE 802.11 specifications used for Wi-Fi, also use microwaves in the 2.4 GHz ISM band , although 802.11a uses ISM band and U-NII frequencies in
2808-576: The earth station in Andover, Maine. The message was relayed to the earth station in France, where it was decoded by a second IBM 1401 in La Gaude, France. Telstar 1, which had ushered in a new age of the commercial use of technology, became a victim of the military technology of the Cold War era. The day before Telstar 1 launched, a U.S. high-altitude nuclear bomb (called Starfish Prime ) had energized
2880-819: The earth's surface as ground waves , or reflect from the ionosphere , so terrestrial microwave communication links are limited by the visual horizon to about 40 miles (64 km). At the high end of the band, they are absorbed by gases in the atmosphere, limiting practical communication distances to around a kilometer. Microwaves are widely used in modern technology, for example in point-to-point communication links, wireless networks , microwave radio relay networks, radar , satellite and spacecraft communication , medical diathermy and cancer treatment, remote sensing , radio astronomy , particle accelerators , spectroscopy , industrial heating, collision avoidance systems , garage door openers and keyless entry systems , and for cooking food in microwave ovens . Microwaves occupy
2952-574: The electrical portions of the azimuth-elevation system that steered the antennas. The antennas were housed in radomes the size of a 14-story office building. Two of these antennas were used, one in Andover, Maine, and the other in France at Pleumeur-Bodou . The GPO antenna at Goonhilly Downs in Great Britain was a conventional 26-meter-diameter paraboloid. Telstar 1 relayed its first, and non-public, television pictures—a flag outside Andover Earth Station—to Pleumeur-Bodou on July 11, 1962. Almost two weeks later, on July 23, at 3:00 p.m. EDT , it relayed
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3024-528: The entire super high frequency (SHF) band (3 to 30 GHz, or 10 to 1 cm) at minimum. A broader definition includes UHF and extremely high frequency (EHF) ( millimeter wave ; 30 to 300 GHz) bands as well. Frequencies in the microwave range are often referred to by their IEEE radar band designations: S , C , X , K u , K , or K a band , or by similar NATO or EU designations. Microwaves travel by line-of-sight ; unlike lower frequency radio waves , they do not diffract around hills, follow
3096-406: The equator, with perigee about 952 km (592 mi) from Earth and apogee about 5,933 km (3,687 mi) from Earth This is in contrast to the 1965 Early Bird Intelsat and subsequent satellites that travel in circular geostationary orbits . Due to its non- geosynchronous orbit , similar to a Molniya orbit , availability of Telstar 1 for transatlantic signals was limited to
3168-984: The first publicly available live transatlantic television signal. The broadcast was shown in Europe by Eurovision and in North America by NBC , CBS , ABC , and the CBC . The first public broadcast featured CBS's Walter Cronkite and NBC's Chet Huntley in New York , and the BBC's Richard Dimbleby in Brussels . The first pictures were the Statue of Liberty in New York and the Eiffel Tower in Paris. The first broadcast
3240-537: The first satellite used to synchronize time between two continents, bringing the United Kingdom and the United States to within 1 microsecond of each other (previous efforts were accurate to only 2,000 microseconds). The Telstar 1 satellite also relayed computer data between two IBM 1401 computers. The test, performed on October 25, 1962, sent a message from a transmitting computer in Endicott, New York , to
3312-423: The first television pictures, telephone calls, and telegraph images , and provided the first live transatlantic television feed. Telstar 2 was launched May 7, 1963. Telstar 1 and 2—though no longer functional—still orbit the Earth. Belonging to AT&T , the original Telstar was part of a multi-national agreement among AT&T (USA), Bell Telephone Laboratories (USA), NASA (USA), GPO (United Kingdom) and
3384-414: The frequency can then be calculated. A similar technique is to use a slotted waveguide or slotted coaxial line to directly measure the wavelength. These devices consist of a probe introduced into the line through a longitudinal slot so that the probe is free to travel up and down the line. Slotted lines are primarily intended for measurement of the voltage standing wave ratio on the line. However, provided
3456-406: The frequency of the microwave oven. Microwave heating is used in industrial processes for drying and curing products. Many semiconductor processing techniques use microwaves to generate plasma for such purposes as reactive ion etching and plasma-enhanced chemical vapor deposition (PECVD). Microwaves are used in stellarators and tokamak experimental fusion reactors to help break down
3528-458: The gas into a plasma and heat it to very high temperatures. The frequency is tuned to the cyclotron resonance of the electrons in the magnetic field, anywhere between 2–200 GHz, hence it is often referred to as Electron Cyclotron Resonance Heating (ECRH). The upcoming ITER thermonuclear reactor will use up to 20 MW of 170 GHz microwaves. Microwaves can be used to transmit power over long distances, and post- World War 2 research
3600-718: The handover. The others were renamed the Intelsat Americas 5, 6, etc. At the time of the sale, Telstar 8 was still under construction by Space Systems/Loral , and it was finally launched on June 23, 2005, by Sea Launch . Telstar 18 was launched in June 2004 by sea launch. The upper stage of the rocket underperformed, but the satellite used its significant stationkeeping fuel margin to achieve its operational geostationary orbit . It has enough on-board fuel remaining to allow it to exceed its specified 13-year design life. Telesat launched Telstar 12 Vantage in November 2015 on
3672-459: The high cost and maintenance requirements of waveguide runs, in many microwave antennas the output stage of the transmitter or the RF front end of the receiver is located at the antenna. The term microwave also has a more technical meaning in electromagnetics and circuit theory . Apparatus and techniques may be described qualitatively as "microwave" when the wavelengths of signals are roughly
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#17327872715463744-577: The low-microwave/high-UHF frequencies around 1.8 and 1.9 GHz in the Americas and elsewhere, respectively. DVB-SH and S-DMB use 1.452 to 1.492 GHz, while proprietary/incompatible satellite radio in the U.S. uses around 2.3 GHz for DARS . Microwave radio is used in point-to-point telecommunications 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
3816-759: The main frequencies used in radar. Microwave radar is widely used for applications such as air traffic control , weather forecasting, navigation of ships, and speed limit enforcement . Long-distance radars use the lower microwave frequencies since at the upper end of the band atmospheric absorption limits the range, but millimeter waves are used for short-range radar such as collision avoidance systems . Microwaves emitted by astronomical radio sources ; planets, stars, galaxies , and nebulas are studied in radio astronomy with large dish antennas called radio telescopes . In addition to receiving naturally occurring microwave radiation, radio telescopes have been used in active radar experiments to bounce microwaves off planets in
3888-520: The origin of the Universe . Microwave technology is extensively used for point-to-point telecommunications (i.e., non-broadcast uses). Microwaves are especially suitable for this use since they are more easily focused into narrower beams than radio waves, allowing frequency reuse ; their comparatively higher frequencies allow broad bandwidth and high data transmission rates , and antenna sizes are smaller than at lower frequencies because antenna size
3960-621: The out. From there, the video switched first to Washington, DC; then to Cape Canaveral , Florida; to the Seattle World's Fair ; then to Quebec and finally to Stratford, Ontario . The Washington segment included remarks by President Kennedy, talking about the price of the American dollar , which was causing concern in Europe. When Kennedy denied that the United States would devalue the dollar it immediately strengthened on world markets; Cronkite later said that "we all glimpsed something of
4032-425: The printed circuit inverted F antenna (PIFA) used in cell phones. Their short wavelength also allows narrow beams of microwaves to be produced by conveniently small high gain antennas from a half meter to 5 meters in diameter. Therefore, beams of microwaves are used for point-to-point communication links, and for radar . An advantage of narrow beams is that they do not interfere with nearby equipment using
4104-639: The same as the dimensions of the circuit, so that lumped-element circuit theory is inaccurate, and instead distributed circuit elements and transmission-line theory are more useful methods for design and analysis. As a consequence, practical microwave circuits tend to move away from the discrete resistors , capacitors , and inductors used with lower-frequency radio waves . Open-wire and coaxial transmission lines used at lower frequencies are replaced by waveguides and stripline , and lumped-element tuned circuits are replaced by cavity resonators or resonant stubs . In turn, at even higher frequencies, where
4176-406: The same frequency, allowing frequency reuse by nearby transmitters. Parabolic ("dish") antennas are the most widely used directive antennas at microwave frequencies, but horn antennas , slot antennas and lens antennas are also used. Flat microstrip antennas are being increasingly used in consumer devices. Another directive antenna practical at microwave frequencies is the phased array ,
4248-528: The signals in a traveling-wave tube, and retransmitted them omnidirectionally via the adjacent array of larger box-shaped cavities. The prominent helical antenna received telecommands from a ground station. Launched by NASA aboard a Delta rocket from Cape Canaveral on July 10, 1962, Telstar 1 was the first privately sponsored space launch. A medium-altitude satellite, Telstar was placed into an elliptical orbit completed once every 2 hours and 37 minutes, inclined at an angle of approximately 45 degrees to
4320-898: The sky, a small amount of the power will be randomly scattered as the beam passes through the troposphere . A sensitive receiver beyond the horizon with a high gain antenna focused on that area of the troposphere can pick up the signal. This technique has been used at frequencies between 0.45 and 5 GHz in tropospheric scatter (troposcatter) communication systems to communicate beyond the horizon, at distances up to 300 km. The short wavelengths of microwaves allow omnidirectional antennas for portable devices to be made very small, from 1 to 20 centimeters long, so microwave frequencies are widely used for wireless devices such as cell phones , cordless phones , and wireless LANs (Wi-Fi) access for laptops , and Bluetooth earphones. Antennas used include short whip antennas , rubber ducky antennas , sleeve dipoles , patch antennas , and increasingly
4392-651: The solar system, to determine the distance to the Moon or map the invisible surface of Venus through cloud cover. A recently completed microwave radio telescope is the Atacama Large Millimeter Array , located at more than 5,000 meters (16,597 ft) altitude in Chile, which observes the universe in the millimeter and submillimeter wavelength ranges. The world's largest ground-based astronomy project to date, it consists of more than 66 dishes and
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#17327872715464464-433: The surface of the Earth, microwave communication links are limited by the visual horizon to about 30–40 miles (48–64 km). Microwaves are absorbed by moisture in the atmosphere, and the attenuation increases with frequency, becoming a significant factor ( rain fade ) at the high end of the band. Beginning at about 40 GHz, atmospheric gases also begin to absorb microwaves, so above this frequency microwave transmission
4536-464: The temperature of objects or terrain. The sun and other astronomical radio sources such as Cassiopeia A emit low level microwave radiation which carries information about their makeup, which is studied by radio astronomers using receivers called radio telescopes . The cosmic microwave background radiation (CMBR), for example, is a weak microwave noise filling empty space which is a major source of information on cosmology 's Big Bang theory of
4608-625: The true power of the instrument we had wrought." That evening, Telstar 1 also relayed the first satellite telephone call , between U.S. vice-president Lyndon Johnson and the chairman of AT&T, Frederick Kappel . It successfully transmitted faxes, data, and both live and taped television, including the first live transmission of television across an ocean from Andover, Maine, US, to Goonhilly Downs, England, and Pleumeur-Bodou, France. (An experimental passive satellite, Echo 1 , had been used to reflect and redirect communications signals two years earlier, in 1960.) In August 1962, Telstar 1 became
4680-410: The wavelength of the electromagnetic waves becomes small in comparison to the size of the structures used to process them, microwave techniques become inadequate, and the methods of optics are used. High-power microwave sources use specialized vacuum tubes to generate microwaves. These devices operate on different principles from low-frequency vacuum tubes, using the ballistic motion of electrons in
4752-471: Was at Goonhilly Downs , Cornwall. The BBC , as international coordinator, used this location. The standards 525 / 405 conversion equipment (filling a large room) was researched and developed by the BBC and located in the BBC Television Centre , London. The French ground station was at Pleumeur-Bodou . The Canadian ground station was at Charleston, Nova Scotia . The German ground station
4824-547: Was at Raisting in Bavaria . The Italian ground station ( Fucino Space Centre ) was at Fucino , near Avezzano , in Abruzzo . The satellite was built by a team at Bell Telephone Laboratories that included John Robinson Pierce , who created the project; Rudy Kompfner , who invented the traveling-wave tube transponder that the satellite used; and James M. Early , who designed its transistors and solar panels. The satellite
4896-416: Was built in an international collaboration by Europe, North America, East Asia and Chile. A major recent focus of microwave radio astronomy has been mapping the cosmic microwave background radiation (CMBR) discovered in 1964 by radio astronomers Arno Penzias and Robert Wilson . This faint background radiation, which fills the universe and is almost the same in all directions, is "relic radiation" from
4968-443: Was done to examine possibilities. NASA worked in the 1970s and early 1980s to research the possibilities of using solar power satellite (SPS) systems with large solar arrays that would beam power down to the Earth's surface via microwaves. Less-than-lethal weaponry exists that uses millimeter waves to heat a thin layer of human skin to an intolerable temperature so as to make the targeted person move away. A two-second burst of
5040-493: Was observed that individuals in the radiation path of radar installations experienced clicks and buzzing sounds in response to microwave radiation. Research by NASA in the 1970s has shown this to be caused by thermal expansion in parts of the inner ear. In 1955, Dr. James Lovelock was able to reanimate rats chilled to 0 and 1 °C (32 and 34 °F) using microwave diathermy. When injury from exposure to microwaves occurs, it usually results from dielectric heating induced in
5112-633: Was renamed Telstar 3C after it was carried into space by Shuttle mission STS-41-D ), and by Telstar 303 in 1985. The next wave, starting with Telstar 401 , came in 1993; which was lost in 1997 due to a magnetic storm, and then Telstar 402 was destroyed shortly after launch in 1994. It was replaced in 1995 by Telstar 402R, eventually renamed Telstar 4 . Telstar 10 was launched in China in 1997 by APT Satellite Company, Ltd. In 2003, Telstars 4–8 and 13— Loral Skynet 's North American fleet—were sold to Intelsat . Telstar 4 suffered complete failure prior to
5184-623: Was to have included remarks by President John F. Kennedy , but the signal was acquired before the president was ready, so engineers filled the lead-in time with a short segment of a televised game between the Philadelphia Phillies and the Chicago Cubs at Wrigley Field . The Phillies' second baseman Tony Taylor was seen hitting a ball pitched by the Cubs' Cal Koonce to deep right field, caught by fielder George Altman for
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