This article is about the microwave spectrum. For the Super NES and Sega Genesis online adapter, see XBAND. For the extension to the mediumwave broadcast band, see AM expanded band. For the radiation band that is not RF, see X-ray. For musical artists using the name X, see X (disambiguation).
X band is often used in modern radars. The shorter wavelengths of the X band provide higher-resolution imagery from high-resolutionimaging radars for 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.[3]
Terrestrial communications and networking
X band 10.15 to 10.7 GHz segment is used for terrestrial broadband in many countries, such as Brazil, Mexico, Saudi Arabia, Denmark, Ukraine, Spain and Ireland.[4]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 providing cable internet to customers, uses some X band frequencies. 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.
Small portions of the X band are assigned by the International Telecommunication Union (ITU) exclusively for deep space telecommunications. The primary user of this allocation is the American NASADeep Space Network (DSN). DSN facilities are in Goldstone, California (in the Mojave Desert), near Canberra, Australia, and near Madrid, Spain, and provide continual communications from the Earth to almost any point in the Solar System independent of Earth rotation. (DSN stations are also 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.)
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.[citation needed]
The new European double Mars Mission ExoMars 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.[citation needed]
1. Essential military requirements for satellite downlinks; the mobile satellite sub-band 7250-7300 MHz is for naval and land mobile earth stations. 2. Military requirement for fixed systems in some countries.
1. This is a harmonised NATO band type 1 for 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 transportable earth stations cannot claim protection
from the other services.
7750-7900 MHz
FIXED
Military requirements for existing NATO fixed systems in some countries.
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.
Motion detectors often use 10.525 GHz.[8] 10.4 GHz is proposed for traffic light crossing detectors.
Comreg in Ireland has allocated 10.450 GHz for Traffic Sensors as SRD.[9]
Particle accelerators may be powered by X-band RF sources. The frequencies are then standardized at 11.9942 GHz (Europe) or 11.424 GHz (US),[10][11] which is the second harmonic of C-band and fourth harmonic of S-band. The European X-band frequency is used for the Compact Linear Collider (CLIC).
^Matrosov, S. Y., Kennedy, P. C. and Cifelli, R., 2014. Experimentally based estimates of relations between X-band radar signal attenuation characteristics and differential phase in rain. Journal of Atmospheric and Oceanic Technology, 31(11), pp. 2442–2450.
^F. Peauger, A. Hamdi, S. Curt, S. Doebert, G. McMonagle, G. Rossat, K.M. Schirm, I. Syratchev, L. Timeo, S. Kuzikhov, A.A. Vikharev, A. Haase, D. Sprehn, A. Jensen, E.N. Jongewaard, C.D. Nantista and A. Vlieks: A 12 GHz RF POWER SOURC E FOR THE CLIC STUDY
