X band

This article is about the microwave spectrum. For the Super NES and Sega Genesis online adapter, seeXBAND.For the extension to the mediumwave broadcast band, seeAM expanded band.For the radiation band that is not RF, seeX-ray.For musical artists using the name X, seeX (disambiguation).

IEEE X band

Frequency range	8.0–12.0GHz
Wavelength range	3.75–2.5cm
Related bands	I/J bands(NATO) SHF(ITU)

TheX bandis the designation for a band offrequenciesin themicrowaveradioregion of theelectromagnetic spectrum.In some cases, such as incommunication engineering,thefrequencyrange of the X band is rather indefinitely set at approximately 7.0–11.2GHz.Inradarengineering, the frequency range is specified by theInstitute of Electrical and Electronics Engineers(IEEE) as 8.0–12.0 GHz. The X band is used forradar,satellite communication,andwireless computer networks.

Radar

See also:Sea-based X-band Radar,AN/TPY-2,AN/SPY-3,andAN/MPQ-64 Sentinel

An X-bandmarine radarantenna on a ship

X band is used in radar applications, includingcontinuous-wave,pulsed, single-polarization,dual-polarization,synthetic aperture radar,andphased arrays.X-band radar frequency sub-bands are used incivil,military,andgovernmentinstitutions forweather monitoring,air traffic control,maritime vessel traffic control,defense tracking,andvehicle speed detectionfor law enforcement.

X band is often used in modern radars. The shorterwavelengthsof the X band provide higher-resolution imagery fromhigh-resolutionimaging radarsfor target identification and discrimination. X-band weather radars offer significant potential for short-range observations, but the loss of signal strength (attenuation) under rainy conditions limits their use at longer range.

Terrestrial communications and networking

X band 10.15 to 10.7 GHz segment is used for terrestrialbroadbandin many countries, such as Brazil, Mexico, Saudi Arabia, Denmark, Ukraine, Spain and Ireland.Alvarion,CBNL,CableFree and Ogier make systems for this, though each has a proprietary airlink.DOCSIS(Data Over Cable Service Interface Specification) the standard used for providingcable internetto customers, uses some X band frequencies. The home / BusinessCPEhas 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_uband satellite TV LNB. Two way applications such as broadband typically use a 350 MHz TX offset.

Space communications

Further information:X Band Satellite Communication

Space communications for science and research

DSS-4370 meter X-band spacecraft communication antenna at theCanberra Deep Space Communication Complex,Australia.

Small portions of the X band are assigned by theInternational Telecommunication Union(ITU) exclusively for deep space telecommunications. The primary user ofthis allocationis the AmericanNASADeep Space Network(DSN). DSN facilities are inGoldstone, California(in theMojave Desert), nearCanberra, Australia,and nearMadrid, Spain,and provide continual communications from the Earth to almost any point in theSolar Systemindependent of Earth rotation. (DSN stations are also capable of using the older and lowerS banddeep-space radio communications allocations, and some higher frequencies on a more-or-less experimental basis, such as in theK band.)

Notable deepspace probeprograms that have employed X band communications include theViking Mars landers;theVoyagermissions toJupiter,Saturn,and beyond; theGalileo Jupiter orbiter;theNew Horizonsmission toPlutoand theKuiper belt,theCuriosity roverand theCassini-HuygensSaturn orbiter.

An important use of the X band communications came with the twoViking programlanders. 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 byDSNground stations. By making simultaneous measurements at the two different frequencies, the resulting data enabled theoretical physicists to verify the mathematical predictions ofAlbert Einstein'sGeneral Theory of Relativity.These results are some of the best confirmations of the General Theory of Relativity.

The new European double Mars MissionExoMarswill 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

TheInternational Telecommunication Union(ITU), the international body which allocates radio frequencies for civilian use, is not authorised to allocate frequency bands for militaryradio communication.This is also the case pertaining toX bandmilitarycommunications satellites.However, in order to meet military radio spectrum requirements, e.g. forfixed-satellite serviceandmobile-satellite service,theNATOnations negotiated theNATO Joint Civil/Military Frequency Agreement(NJFA).

(a)	(b)	(c)	(d)
7250-7750 MHz	FIXED FIXED-SATELLlTE (s-E), MOBILE-SATELLlTE (s-E) (S5.461)	1. Essential military requirements for satellite downlinks; the mobile satellite sub-band 7250-7300 MHz is for naval andland mobile earth stations. 2. Military requirement for fixed systems in some countries.	1. This is a harmonisedNATO band type 1for satellite downlinks. 2. 7250-7300 MHz is paired with 7975-8025 MHz for the MOBILE-SATELLlTE allocation. 3. The FIXED and MOBILE services are not to be implemented in the band 7250-7300 MHz in most NATO countries, including ITU Region 2. 4. In the band 7300-7750 MHz the transportableearth stationscannot claim protection from the other services.
7750-7900 MHz	FIXED	Military requirements for existing NATO fixed systems in some countries.
7900-8400 MHz	FIXED-SATELLlTE (E-s), MOBILE-SATELLlTE (E-s) (S5.461), FIXED Earth exploration-satellite(s-E) (S5.462A),	1. Essential military requirements for satellite uplinks; the mobile satellite sub-band 7975-8025 MHz is for naval and land mobile satellite earth stations. 2. Military requirement for earth exploration satellite (downlink) purposes in the band 8025-8400 MHz. 3. Military requirement for fixed systems in some countries.	1. This is a harmonised NATO band type 1 for satellite uplinks. 2. 7975-8025 MHz is paired with 7250-7300 MHz for the MOBILE-SATELLlTE allocation. 3. The FIXED and MOBILE services are not to be implemented in 7975-8025 MHz in most NATO countries, including ITU Region 2. 4. In the bands 7900-7975 and 8025-8400 MHz the transportable earth stations must not cause harmful interference to other services.
8500 MHz- 10.5 GHz	RADIOLOCATION Radiolocation	Military requirement for land, airborne and naval radars.	Harmonised NATO band type 2 in selected sub-bands is desirable.

Amateur radio

The Radio Regulations of theInternational Telecommunication Unionallowamateur radiooperations in the frequency range 10.000 to 10.500 GHz,andamateur satelliteoperations are allowed in the range 10.450 to 10.500 GHz. This is known as the3-centimeter bandby amateurs and the X-band byAMSAT.

Other uses

Motion detectorsoften use 10.525 GHz.10.4 GHz is proposed fortraffic lightcrossing detectors. Comreg in Ireland has allocated 10.450 GHz for Traffic Sensors as SRD.

Manyelectron paramagnetic resonance(EPR) spectrometers operate near 9.8 GHz.

Particle acceleratorsmay be powered by X-bandRFsources. The frequencies are then standardized at 11.9942 GHz (Europe) or 11.424 GHz (US),which is the second harmonic ofC-bandand fourth harmonic ofS-band.The European X-band frequency is used for theCompact Linear Collider (CLIC).

See also

• Cassegrain reflector
• Directional antenna
• XTAR
• Sea-based X band Radar
• New Horizons telecommunications
• Voyager program#Spacecraft design
• Earth observation satellites transmission frequencies
• TerraSAR-X:a German Earth observation satellite

External links

• United States Frequency Allocations
• 10GHz wideband transceiver