The X band is the designation for a band of

frequencies Frequency is the number of occurrences of a repeating event per unit of time. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio ...

in the

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 frequency, frequencies between 300&n ...

radio Radio is the technology of communicating using radio waves. Radio waves are electromagnetic waves of frequency between 3 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connec ...

region of the

electromagnetic spectrum The electromagnetic spectrum is the full range of electromagnetic radiation, organized by frequency or wavelength. The spectrum is divided into separate bands, with different names for the electromagnetic waves within each band. From low to high ...

. In some cases, such as in

communication engineering Telecommunications engineering is a subfield of electronics engineering which seeks to design and devise systems of communication at a distance. The work ranges from basic circuit design to strategic mass developments. A telecommunication engi ...

, the frequency range of the X band is set at approximately 7.0–11.2

GHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or Cycle per second, cycle) per second. The hertz is an SI derived unit whose formal expression in ter ...

. In

radar Radar is a system that uses radio waves to determine the distance ('' ranging''), direction ( azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track ...

engineering, the frequency range is specified by the

Institute of Electrical and Electronics Engineers The Institute of Electrical and Electronics Engineers (IEEE) is an American 501(c)(3) public charity professional organization for electrical engineering, electronics engineering, and other related disciplines. The IEEE has a corporate office ...

(IEEE) as 8.0–12.0 GHz. The X band is used for radar,

satellite communication A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth. ...

, and wireless computer networks.

Radar

X band is used in radar applications, including

continuous-wave A continuous wave or continuous waveform (CW) is an electromagnetic wave of constant amplitude and frequency, typically a sine wave, that for mathematical analysis is considered to be of infinite duration. It may refer to e.g. a laser or particle ...

, pulsed, single- polarization, dual-polarization,

synthetic aperture radar Synthetic-aperture radar (SAR) is a form of radar that is used to create two-dimensional images or 3D reconstruction, three-dimensional reconstructions of objects, such as landscapes. SAR uses the motion of the radar antenna over a target regi ...

, and

phased array In antenna (radio), antenna theory, a phased array usually means an electronically scanned array, a computer-controlled Antenna array, array of antennas which creates a radio beam, beam of radio waves that can be electronically steered to point ...

s. X-band radar frequency sub-bands are used in

civil Civil may refer to: *Civility, orderly behavior and politeness *Civic virtue, the cultivation of habits important for the success of a society *Civil (journalism) ''The Colorado Sun'' is an online news outlet based in Denver, Colorado. It lau ...

military A military, also known collectively as armed forces, is a heavily armed, highly organized force primarily intended for warfare. Militaries are typically authorized and maintained by a sovereign state, with their members identifiable by a d ...

, and

government A government is the system or group of people governing an organized community, generally a State (polity), state. In the case of its broad associative definition, government normally consists of legislature, executive (government), execu ...

institutions for weather monitoring,

air traffic control Air traffic control (ATC) is a service provided by ground-based air traffic controllers who direct aircraft on the ground and through a given section of controlled airspace, and can provide advisory services to aircraft in non-controlled air ...

, maritime vessel traffic control, defense tracking, and vehicle speed detection for law enforcement. X band is often used in modern radars. The shorter

wavelength In physics and mathematics, wavelength or spatial period of a wave or periodic function is the distance over which the wave's shape repeats. In other words, it is the distance between consecutive corresponding points of the same ''phase (waves ...

s of the X band provide higher-resolution imagery from

high-resolution Image resolution is the level of detail of an image. The term applies to digital images, film images, and other types of images. "Higher resolution" means more image detail. Image resolution can be measured in various ways. Resolution quantifies ...

imaging radar Imaging radar is an application of radar which is used to create two-dimensional images, typically of landscapes. Imaging radar provides its light to illuminate an area on the ground and take a picture at radio wavelengths. It uses an antenna and ...

s for target identification and discrimination. X-band weather radars offer significant potential for short-range observations, but the loss of signal strength (

attenuation In physics, attenuation (in some contexts, extinction) is the gradual loss of flux intensity through a Transmission medium, medium. For instance, dark glasses attenuate sunlight, lead attenuates X-rays, and water and air attenuate both light and ...

) under rainy conditions limits their use at longer range.

Terrestrial communications and networking

The X band 10.15 to 10.7 GHz segment is used for terrestrial

broadband In telecommunications, broadband or high speed is the wide-bandwidth (signal processing), bandwidth data transmission that exploits signals at a wide spread of frequencies or several different simultaneous frequencies, and is used in fast Inter ...

in many countries, such as Brazil, Mexico, Saudi Arabia, Denmark, Ukraine, Spain and Ireland.

Alvarion Alvarion Technologies Ltd. is a global provider of autonomous Wi-Fi networks designed with self-organizing capabilities for carrier-grade Wi-Fi, enterprise connectivity, smart city planning, smart hospitality, connected campuses, and connected e ...

, CBNL, CableFree and Ogier make systems for this, though each has a proprietary airlink.

DOCSIS Data Over Cable Service Interface Specification (DOCSIS) is an international telecommunications standard that permits the addition of high-bandwidth data transfer to an existing cable television (CATV) system. It is used by many cable televisio ...

(Data Over Cable Service Interface Specification) the standard used for providing

cable internet In telecommunications, cable Internet access, shortened to cable Internet, is a form of broadband internet access which uses the same infrastructure as cable television. Like digital subscriber line (DSL) and fiber to the premises, cable Internet ...

to customers, uses some X band frequencies. The home / business

customer-premises equipment In telecommunications, a customer-premises equipment or customer-provided equipment (CPE) is any terminal and associated equipment located at a subscriber's premises and connected with a carrier's telecommunication circuit at the demarcation p ...

(CPE) has a single coaxial cable with a power adapter connecting to an ordinary cable modem. The local oscillator is usually 9750 MHz, the same as for K_u band satellite TV LNB. Two way applications such as broadband typically use a 350 MHz TX offset.

Space communications

Space communications for science and research

Canberra Deep Dish Communications Complex - GPN-2000-000502

Small portions of the X band are assigned by the

International Telecommunication Union The International Telecommunication Union (ITU)In the other common languages of the ITU: * * is a list of specialized agencies of the United Nations, specialized agency of the United Nations responsible for many matters related to information ...

(ITU) exclusively for deep space telecommunications. The primary user of this allocation is the American

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

Deep Space Network The NASA Deep Space Network (DSN) is a worldwide Telecommunications network, network of spacecraft communication ground segment facilities, located in the United States (California), Spain (Madrid), and Australia (Canberra), that supports NASA' ...

(DSN). DSN facilities are in

Goldstone, California The Goldstone Deep Space Communications Complex (GDSCC), commonly called the Goldstone Observatory, is a satellite ground station located in Fort Irwin in the U.S. state of California. Operated by NASA's Jet Propulsion Laboratory (JPL), its mai ...

(in the

Mojave Desert The Mojave Desert (; ; ) is a desert in the rain shadow of the southern Sierra Nevada mountains and Transverse Ranges in the Southwestern United States. Named for the Indigenous peoples of the Americas, indigenous Mohave people, it is located pr ...

), near

Canberra, Australia Canberra ( ; ) is the capital city of Australia. Founded following the federation of the colonies of Australia as the seat of government for the new nation, it is Australia's largest inland city, and the eighth-largest Australian city b ...

, and near

Madrid, Spain Madrid ( ; ) is the capital and List of largest cities in Spain, most populous municipality of Spain. It has almost 3.5 million inhabitants and a Madrid metropolitan area, metropolitan area population of approximately 7 million. It i ...

, and provide continual communications from the Earth to almost any point in the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...

independent of Earth rotation. (DSN stations are also capable of using the older and lower

S band The S band is a designation by the Institute of Electrical and Electronics Engineers (IEEE) for a part of the microwave band of the electromagnetic spectrum covering frequencies from 2 to 4 gigahertz (GHz). Thus it crosses the conventiona ...

deep-space radio communications allocations, and some higher frequencies on a more-or-less experimental basis, such as in the K band.) Notable deep

space probe Uncrewed spacecraft or robotic spacecraft are spacecraft without people on board. Uncrewed spacecraft may have varying levels of autonomy from human input, such as remote control, or remote guidance. They may also be autonomous, in which th ...

programs that have employed X band communications include the Viking Mars landers; the Voyager missions to

Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined a ...

Saturn Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about 9 times that of Earth. It has an eighth the average density of Earth, but is over 95 tim ...

, and beyond; the Galileo Jupiter orbiter; the

New Horizons ''New Horizons'' is an Interplanetary spaceflight, interplanetary space probe launched as a part of NASA's New Frontiers program. Engineered by the Johns Hopkins University Applied Physics Laboratory (APL) and the Southwest Research Institut ...

mission to

Pluto Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of Trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Su ...

and the

Kuiper belt The Kuiper belt ( ) is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical units (AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger—20 times ...

, the

Curiosity rover ''Curiosity'' is a car-sized Mars rover Space exploration, exploring Gale (crater), Gale crater and Mount Sharp on Mars as part of NASA's Mars Science Laboratory (MSL) mission. ''Curiosity'' was launched from Cape Canaveral Space Force Station ...

and the Cassini-Huygens Saturn orbiter. An important use of the X band communications came with the two

Viking program The ''Viking'' program consisted of a pair of identical American space probes, ''Viking 1'' and ''Viking 2'' both launched in 1975, and landed on Mars in 1976. The mission effort began in 1968 and was managed by the NASA Langley Research Cent ...

landers. When the planet Mars was passing near or behind the Sun, as seen from the Earth, a Viking lander would transmit two simultaneous continuous-wave carriers, one in the S band and one in the X band in the direction of the Earth, where they were picked up by DSN ground stations. By making simultaneous measurements at the two different frequencies, the resulting data enabled theoretical physicists to verify the mathematical predictions of

Albert Einstein Albert Einstein (14 March 187918 April 1955) was a German-born theoretical physicist who is best known for developing the theory of relativity. Einstein also made important contributions to quantum mechanics. His mass–energy equivalence f ...

General Theory of Relativity General relativity, also known as the general theory of relativity, and as Einstein's theory of gravity, is the geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physi ...

. These results are some of the best confirmations of the General Theory of Relativity. The new European double Mars Mission

ExoMars ExoMars (Exobiology on Mars) is an astrobiology programme of the European Space Agency (ESA). The goals of ExoMars are to search for signs of past life on Mars, investigate how the Martian water and geochemical environment varies, investigate ...

will also use X band communication, on the instrument LaRa, to study the internal structure of Mars, and to make precise measurements of the rotation and orientation of Mars by monitoring two-way Doppler frequency shifts between the surface platform and Earth. It will also detect variations in angular momentum due to the redistribution of masses, such as the migration of ice from the polar caps to the atmosphere.

X band NATO frequency requirements

The International Telecommunication Union (ITU), the international body which allocates radio frequencies for civilian use, is not authorised to allocate frequency bands for military

radio communication Radio is the technology of telecommunication, communicating using radio waves. Radio waves are electromagnetic waves of frequency between 3 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transm ...

. This is also the case pertaining to X band military

communications satellite A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a Transponder (satellite communications), transponder; it creates a communication channel between a source transmitter and a Rad ...

s. However, in order to meet military radio spectrum requirements, e.g. for fixed-satellite service and

mobile-satellite service Mobile-satellite service (MSS, or mobile-satellite radiocommunication service) is – according to Article 1.25 of the International Telecommunication Union's Radio Regulations – "A radiocommunication service * between mobile earth stations and ...

, the

NATO The North Atlantic Treaty Organization (NATO ; , OTAN), also called the North Atlantic Alliance, is an intergovernmental organization, intergovernmental Transnationalism, transnational military alliance of 32 Member states of NATO, member s ...

nations negotiated the NATO Joint Civil/Military Frequency Agreement (NJFA).

Amateur radio

The Radio Regulations of the International Telecommunication Union allow

amateur radio Amateur radio, also known as ham radio, is the use of the radio frequency radio spectrum, spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emer ...

operations in the frequency range 10.000 to 10.500 GHz, and

amateur satellite An amateur radio satellite is an artificial satellite built and used by amateur radio operators. It forms part of the Amateur-satellite service. These satellites use amateur radio frequency allocations to facilitate communication between amate ...

operations are allowed in the range 10.450 to 10.500 GHz. This is known as the 3-centimeter band by amateurs and the X-band by

AMSAT AMSAT is a name for various amateur radio satellite organizations worldwide. In particular, it often refers to the Radio Amateur Satellite Corporation, headquartered in Washington, D.C. AMSAT organizations design, build, arrange launches for, a ...

Other uses

Motion detector A motion detector is an electrical device that utilizes a sensor to detect nearby motion (motion detection). Such a device is often integrated as a Electronic component, component of a system that automatically performs a task or Security alarm, ...

s often use 10.525 GHz. 10.4 GHz is proposed for

traffic light Traffic lights, traffic signals, or stoplights – also known as robots in South Africa, Zambia, and Namibia – are signaling devices positioned at intersection (road), road intersections, pedestrian crossings, and other locations in order t ...

crossing detectors. Comreg in Ireland has allocated 10.450 GHz for traffic sensors as SRD. Many

electron paramagnetic resonance Electron paramagnetic resonance (EPR) or electron spin resonance (ESR) spectroscopy is a method for studying materials that have unpaired electrons. The basic concepts of EPR are analogous to those of nuclear magnetic resonance (NMR), but the spin ...

(EPR) spectrometers operate near 9.8 GHz.

Particle accelerator A particle accelerator is a machine that uses electromagnetic fields to propel electric charge, charged particles to very high speeds and energies to contain them in well-defined particle beam, beams. Small accelerators are used for fundamental ...

s may be powered by X-band RF sources. The frequencies are then standardized at 11.9942 GHz (Europe) or 11.424 GHz (US), which is the second harmonic of C-band and fourth harmonic of

S-band The S band is a designation by the Institute of Electrical and Electronics Engineers (IEEE) for a part of the microwave band of the electromagnetic spectrum covering frequencies from 2 to 4 gigahertz (GHz). Thus it crosses the convention ...

. The European X-band frequency is used for the Compact Linear Collider (CLIC). Many

Radio Astronomy Radio astronomy is a subfield of astronomy that studies Astronomical object, celestial objects using radio waves. It started in 1933, when Karl Jansky at Bell Telephone Laboratories reported radiation coming from the Milky Way. Subsequent observat ...

facilities have receivers which work in the X-band including the

Green Bank Telescope The Robert C. Byrd Green Bank Telescope (GBT) in Green Bank, West Virginia, US is the world's largest fully steerable radio telescope, surpassing the Effelsberg 100-m Radio Telescope in Germany. The Green Bank site was part of the National Rad ...

and the

Very Large Array The Karl G. Jansky Very Large Array (VLA) is a centimeter-wavelength radio astronomy observatory in the southwestern United States built in the 1970s. It lies in central New Mexico on the Plains of San Agustin, between the towns of Magdalena, Ne ...

has a Frequency Allocation for (quiet) bands at 10.6-10.68 GHz, and 10.68-10.7 GHz, but the receivers work across a much wider range of the entire X-band (e.g. 7-12 GHz) trying to take advantages of as much bandwidth as possible to be sensitive to faint astronomical sources.

References

External links

United States Frequency Allocations
{{EMSpectrum Microwave bands Radar Radio frequency propagation