X band

From Wikipedia, the free encyclopedia
This article is about the microwave spectrum. For the Super Nintendo and Sega Genesis online adapter, see XBAND. For the radiation band that is not RF, see X-ray. For musical artists with the name X, see X (disambiguation).
X band
Frequency range 8.0–12.0 GHz
(IEEE radar)
ITU Radio Band Numbers

1 2 3 4 5 6 7 8 9 10 11 12

ITU Radio Band Symbols

ELF SLF ULF VLF LF MF HF VHF UHF SHF EHF THF

NATO Radio bands

A B C D E F G H I J K L M

IEEE Radar bands

HF VHF UHF L S C X Ku K Ka V W mm

The X band is a segment of the microwave radio region of the electromagnetic spectrum. In some cases, such as in communication engineering, the frequency range of X band is rather indefinitely set at approximately 7.0 to 11.2 gigahertz (GHz). In radar engineering, the frequency range is specified by the IEEE at 8.0 to 12.0 GHz (8.9 to 9.1 Bel Hz).

The term "X-band" is also used informally and inaccurately to refer to the extended AM broadcast band, where the "X" stands for "extended".

Satellite communications

For military communications satellites, the International Telecommunications Union (ITU) has assigned the X band uplink frequency band (for sending modulated signals) as from 7.9 to 8.4 GHz. The ITU-assigned downlink frequency band (for receiving signals) is from 7.25 to 7.75 GHz. The US military uses all frequencies in this spectrum; however, they use select signals on the frequencies throughout this spectrum. The typical local oscillator frequency of an X band low-noise block converter (LNB) is 6300 MHz. Both of these frequency bands are 500 MHz wide.

In engineering, this pair of frequency bands may be referred to as the 8 / 7 GHz X band satellite communications system.

Radar

An X-Band radar antenna.

X band is used in radar applications including continuous-wave, pulsed, single-polarization, dual-polarization, synthetic aperture radar, and phased arrays. X band radar frequency sub-bands are used in civil, military, and government institutions for weather monitoring, air traffic control, maritime vessel traffic control, defense tracking, and vehicle speed detection for law enforcement.[1]

X band is often used in modern radars. The shorter wavelengths of the X band allow for higher resolution imagery from high-resolution imaging radars for target identification and discrimination.

Terrestrial communications and networking

In Ireland, Libya, Saudi Arabia[citation needed] and Canada, the X band 10.15 to 10.7 segment is used for terrestrial broadband. Alvarion, Cambridge, and Ogier make systems for this, though these are all incompatible. The Ogier system is a full duplex Transverter used for DOCSIS over microwave. The home / Business 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 Ku band satellite TV LNB. Two way applications such as broadband typically use a 350 MHz TX offset.

Space communications

Portions of the X band are assigned by the International Telecommunications Union (ITU) exclusively for deep space telecommunications. The primary user of this allocation is the American NASA Deep Space Network (DSN)[citation needed]. DSN facilities are located in Goldstone, California (in the Mojave Desert), near Canberra, Australia, and near Madrid, Spain.

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.

Notable deep space probe programs that have employed X band communications include the Viking Mars landers; the Voyager missions to Jupiter, Saturn, and beyond; the Galileo Jupiter orbiter; the New Horizons mission to Pluto and the Kuiper belt, the Curiosity rover and the Cassini-Huygens Saturn orbiter.

An important use of the X band communications came with the two Viking program 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's General Theory of Relativity. These results are some of the best confirmations of the General Theory of Relativity.

Amateur radio

The Radio Regulations of the International Telecommunication Union allow amateur radio operations in the frequency range 10.000 to 10.500 GHz,[2] and amateur satellite 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.

Other uses

Motion detectors often use 10.525 GHz.[3] 10.4 GHz is proposed for traffic light crossing detectors. Comreg in Ireland has allocated 10.450 GHz for Traffic Sensors as SRD.[4]

Many electron paramagnetic resonance (EPR) spectrometers operate near 9.8 GHz.

Other microwave bands

The microwave spectrum is usually defined as electromagnetic energy ranging from approximately 1 GHz to 100 GHz in frequency, but older usage includes lower frequencies. Most common applications are within the 1 to 40 GHz range. Microwave frequency bands, as defined by the Radio Society of Great Britain (RSGB), are shown in the table below:

L band1 to 2 GHz
S band2 to 4 GHz
C band4 to 8 GHz
X band8 to 12 GHz
Ku band12 to 18 GHz
K band18 to 26.5 GHz
Ka band26.5 to 40 GHz
Q band30 to 50 GHz
U band40 to 60 GHz
V band50 to 75 GHz
E band60 to 90 GHz
W band75 to 110 GHz
F band90 to 140 GHz
D band110 to 170 GHz

Footnote: P band is sometimes incorrectly used for Ku Band. "P" for "previous" was a radar band used in the UK ranging from 250 to 500 MHz and now obsolete per IEEE Std 521.[5][6] For other definitions see Letter Designations of Microwave Bands

See also

References

  1. ↑ Radar Bands
  2. ↑ VHF Handbook of IARU Region 1 (2006), pg. 50
  3. ↑ 10GHz Wideband Transceiver
  4. ↑ http://www.comreg.ie/radio_spectrum/exemptions.541.488.rslicensing.html
  5. ↑ http://www.radioing.com/eengineer/bands.html
  6. ↑ http://www.microwaves101.com/encyclopedia/letterbands.cfm

External links

ELF
3 Hz/100 Mm
30 Hz/10 Mm

SLF
30 Hz/10 Mm
300 Hz/1 Mm

ULF
300 Hz/1 Mm
3 kHz/100 km

VLF
3 kHz/100 km
30 kHz/10 km

LF
30 kHz/10 km
300 kHz/1 km

MF
300 kHz/1 km
3 MHz/100 m

HF
3 MHz/100 m
30 MHz/10 m

VHF
30 MHz/10 m
300 MHz/1 m

UHF
300 MHz/1 m
3 GHz/100 mm

SHF
3 GHz/100 mm
30 GHz/10 mm

EHF
30 GHz/10 mm
300 GHz/1 mm

THF
300 GHz/1 mm
3 THz/0.1 mm

← higher frequencies       longer wavelengths →

Visible (optical)
Microwaves
Radio
Wavelength types
This article is issued from Wikipedia. The text is available under the Creative Commons Attribution/Share Alike; additional terms may apply for the media files.