The K
u band () is the portion of the
electromagnetic spectrum
The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies.
The electromagnetic spectrum covers electromagnetic waves with frequencies ranging fro ...
in the
microwave
Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively. Different sources define different frequency ra ...
range of frequencies from 12 to 18
gigahertz (GHz). The symbol is short for "K-under" (originally german: Kurz-unten), because it is the lower part of the original
NATO K band, which was split into three bands (K
u,
K, and
Ka) because of the presence of the atmospheric
water vapor
(99.9839 °C)
, -
, Boiling point
,
, -
, specific gas constant
, 461.5 J/( kg·K)
, -
, Heat of vaporization
, 2.27 MJ/kg
, -
, Heat capacity
, 1.864 kJ/(kg·K)
Water vapor, water vapour or aqueous vapor is the gaseous p ...
resonance peak at 22.24 GHz, (1.35 cm) which made the center unusable for long range transmission. In radar applications, it ranges from 12 to 18
GHz according to the formal definition of radar frequency band nomenclature in IEEE Standard 521–2002.
K
u band is primarily used for
satellite communications, most notably the downlink used by
direct broadcast satellite
Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location. The signals are received via an outdoor parabolic antenna comm ...
s to broadcast
satellite television
Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location. The signals are received via an outdoor parabolic antenna com ...
, and for specific applications such as
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research.
NASA was established in 1958, succeedin ...
's
Tracking Data Relay Satellite used for
International Space Station
The International Space Station (ISS) is the largest Modular design, modular space station currently in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos ( ...
(ISS) communications and
SpaceX
Space Exploration Technologies Corp. (SpaceX) is an American spacecraft manufacturer, launcher, and a satellite communications corporation headquartered in Hawthorne, California. It was founded in 2002 by Elon Musk with the stated goal o ...
Starlink satellites. K
u band satellites are also used for
backhauls and particularly for satellite from remote locations back to a
television
Television, sometimes shortened to TV, is a telecommunication medium for transmitting moving images and sound. The term can refer to a television set, or the medium of television transmission. Television is a mass medium for advertising, ...
network's studio for editing and
broadcasting
Broadcasting is the distribution of audio or video content to a dispersed audience via any electronic mass communications medium, but typically one using the electromagnetic spectrum (radio waves), in a one-to-many model. Broadcasting began wi ...
. The band is split by the
International Telecommunication Union
The International Telecommunication Union is a specialized agency of the United Nations responsible for many matters related to information and communication technologies. It was established on 17 May 1865 as the International Telegraph Unio ...
(ITU) into multiple segments that vary by geographical region.
NBC was the first television network to uplink a majority of its affiliate feeds via K
u band in 1983.
Some frequencies in this radio band are employed in
radar guns used by law enforcement to detect vehicles speeding, especially in Europe.
Segments and regions
America
Segments in most of North and South America are represented by
ITU Region
The International Telecommunication Union (ITU), in its International Radio Regulations, divides the world into three ITU regions for the purposes of managing the global radio spectrum. Each region has its own set of frequency allocations, the ...
2 from 11.7 to 12.2 GHz (
Local Oscillator Frequency (LOF) 10.75 to 11.25 GHz), allocated to the FSS (
fixed satellite service),
uplink from 14.0 to 14.5 GHz. There are more than 22 FSS K
u band satellites orbiting over North America, each carrying 12 to 48
transponders
In telecommunications, a transponder is a device that, upon receiving a signal, emits a different signal in response. The term is a blend of ''transmitter'' and ''responder''.
In air navigation or radio frequency identification, a flight tra ...
, 20 to 120
watt
The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after James ...
s per transponder, and requiring a 0.8-m to 1.5-m antenna for clear reception.
The 12.2 to 12.7 GHz (LOF 11.25 to 11.75 GHz) segment is allocated to the BSS (
broadcasting satellite service). BSS (DBS
direct broadcast satellite
Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location. The signals are received via an outdoor parabolic antenna comm ...
s) normally carry 16 to 32 transponders of 27
MHz bandwidth running at 100 to 240 watts of power, allowing the use of receiver antennas as small as 18 inches (450 mm).
Europe and Africa
Segments in those regions are represented by ITU Region 1, and they are the 11.45 to 11.7 and 12.5 to 12.75 GHz bands are allocated to the FSS (
fixed satellite service,
uplink 14.0 to 14.5 GHz). In Europe K
u band is used from 10.7 to 12.75 GHz (LOF Low 9.750 GHz, LOF High 10.600 GHz) for
direct broadcast satellite
Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location. The signals are received via an outdoor parabolic antenna comm ...
services such as those carried by the
Astra satellites. The 11.7 to 12.5 GHz segment is allocated to the BSS (
broadcasting satellite service).
Australia
Australia is part of ITU Region 3 and the Australian regulatory environment provides a class license that covers downlinking from 11.70 GHz to 12.75 GHz and uplinking from 14.0 GHz to 14.5 GHz.
Indonesia
The
ITU
The International Telecommunication Union is a specialized agency of the United Nations responsible for many matters related to information and communication technologies. It was established on 17 May 1865 as the International Telegraph Union ...
has categorized
Indonesia
Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Gui ...
as Region P, countries with very high rain precipitation. This statement has made many people unsure about using K
u-band (11 – 18 GHz) in Indonesia. Using frequencies higher than 10 GHz in a heavy rain area usually gives poor results. This problem can be solved by using an appropriate
link budget when designing the wireless communication link. Higher power can overcome the loss to
rain fade Rain fade refers primarily to the absorption of a microwave radio frequency (RF) signal by atmospheric rain, snow
Snow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, ...
.
Measurements of rain attenuation in Indonesia have been done for satellite communication links in Padang, Cibinong, Surabaya and Bandung. The DAH Model for rain attenuation prediction is valid for Indonesia, as is the ITU model. The DAH model has become an ITU recommendation since 2001 (Recommendation No. ITU-R P.618-7). This model can create a 99.7% available link so that K
u-band can be applied in Indonesia.
Use of the K
u-band for satellite communications in tropical regions like Indonesia is becoming more frequent. Several satellites above Indonesia have K
u-band
transponders, and even
Ka band transponders.
Newskies (NSS 6), launched in December 2002 and positioned at 95° East, contains only K
u-band transponders with a footprint on Indonesia (
Sumatra
Sumatra is one of the Sunda Islands of western Indonesia. It is the largest island that is fully within Indonesian territory, as well as the sixth-largest island in the world at 473,481 km2 (182,812 mi.2), not including adjacent i ...
,
Java
Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's mo ...
,
Borneo
Borneo (; id, Kalimantan) is the third-largest island in the world and the largest in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java, west of Sulawesi, and e ...
,
Celebes,
Bali
Bali () is a province of Indonesia and the westernmost of the Lesser Sunda Islands. East of Java and west of Lombok, the province includes the island of Bali and a few smaller neighbouring islands, notably Nusa Penida, Nusa Lembongan, and ...
,
Nusa Tenggara,
Moluccas). NSS 6 is intended to be replaced by
SES-12 at the same location, which launched in June 2018 and carries 54 K
u-band transponders. The
iPSTAR satellite, launched in 2004 also uses K
u band footprints. Other satellites that provides K
u band covers Indonesia are
Palapa D,
MEASAT
MEASAT Satellite Systems Sdn. Bhd, formerly Binariang Satellite Systems Sdn. Bhd is a Malaysian communications satellite operator, which owns and operates the MEASAT (Malaysia East Asia Satellite) and AFRICASAT spacecraft. The company provides sat ...
3/3A,
JCSAT-4B,
AsiaSat 5, ST 2,
Chinasat 11,
Korea Telecom Koreasat 8/ABS 2 (2nd half 2013), and
SES-8.
Others
Other ITU allocations have been made within the K
u band to the fixed service (microwave towers), radio astronomy service, space research service, mobile service, mobile satellite service, radiolocation service (radar),
amateur radio service, and radionavigation. However, not all of these services are actually operating in this band and others are only minor users.
Advantages
Compared with
C-band, K
u band is not similarly restricted in power to avoid interference with terrestrial microwave systems, and the power of its uplinks and downlinks can be increased. This higher power also translates into smaller receiving dishes and points out a generalization between a satellite's transmission and a dish's size. As the power increases, the size of an antenna's dish will decrease. This is because the purpose of the dish element of the antenna is to collect the incident waves over an area and focus them all onto the antenna's actual receiving element, mounted in front of the dish (and pointed back towards its face); if the waves are more intense, fewer of them need to be collected to achieve the same intensity at the receiving element.
A major attraction of the band over lower frequency microwave bands is that the shorter wavelengths allow sufficient angular resolution to separate the signals of different communication satellites to be achieved with smaller terrestrial
parabolic antenna
A parabolic antenna is an antenna that uses a parabolic reflector, a curved surface with the cross-sectional shape of a parabola, to direct the radio waves. The most common form is shaped like a dish and is popularly called a dish antenna or par ...
s. From the
Rayleigh criterion, the diameter of a parabolic dish required to create a radiation pattern with a given angular
beamwidth
The beam diameter or beam width of an electromagnetic beam is the diameter along any specified line that is perpendicular to the beam axis and intersects it. Since beams typically do not have sharp edges, the diameter can be defined in many differ ...
(
gain
Gain or GAIN may refer to:
Science and technology
* Gain (electronics), an electronics and signal processing term
* Antenna gain
* Gain (laser), the amplification involved in laser emission
* Gain (projection screens)
* Information gain in de ...
) is proportional to the
wavelength
In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats.
It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, tr ...
, and thus inversely proportional to the frequency. At 12 GHz a 1-meter dish is capable of focusing on one satellite while sufficiently rejecting the signal from another satellite only 2 degrees away. This is important because satellites in FSS (Fixed Satellite Service) service (11.7-12.2 GHz in the U.S.) are only 2 degrees apart. At 4 GHz (C-band) a 3-meter dish is required to achieve this narrow angular resolution. Note the inverse linear correlation between dish size and frequency. For K
u satellites in DBS (Direct Broadcast Satellite) service (12.2-12.7 GHz in the U.S.) dishes much smaller than 1-meter can be used because those satellites are spaced 9 degrees apart. As power levels on both C and K
u band satellites have increased over the years, dish beam-width has become much more critical than gain.
The K
u band also offers a user more flexibility. A smaller dish size and a K
u band system's freedom from terrestrial operations simplifies finding a suitable dish site. For the end users K
u band is generally cheaper and enables smaller antennas (both because of the higher frequency and a more focused beam). K
u band is also less vulnerable to rain fade than the K
a band frequency spectrum.
Disadvantages
There are, however, some disadvantages of the K
u band system. Around 10 GHz is the absorption peak due to orientation relaxation of molecules in liquid water. Above 10 GHz,
Mie scattering
The Mie solution to Maxwell's equations (also known as the Lorenz–Mie solution, the Lorenz–Mie–Debye solution or Mie scattering) describes the scattering of an electromagnetic plane wave by a homogeneous sphere. The solution takes the ...
takes over. The effect is a noticeable degradation, commonly known as
rain fade Rain fade refers primarily to the absorption of a microwave radio frequency (RF) signal by atmospheric rain, snow
Snow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, ...
, during heavy rain (100 mm/h).
[TECH-FAQ]
Ku band
This problem can be mitigated by transmitting a higher powered signal from the satellite to compensate. Therefore, the K
u band satellites typically require considerably more power to transmit than the C-band satellites.
Another weather-caused degradation called "snow fade" is not specific to the K
u band. It is due to snow or ice accumulation on a dish significantly altering its focal point.
The satellite operator's Earth station antenna requires more accurate position control when operating at K
u band due to its much narrower beam focus compared to C band for a dish of a given size. Position feedback accuracies are higher and the antenna may require a closed loop control system to maintain position under wind loading of the dish surface.
See also
*
Multifunction Advanced Data Link Multifunction Advanced Data Link (MADL) is a fast switching narrow directional communications data link between stealth aircraft. It began as a method to coordinate between F-35 aircraft (the Joint Strike Fighter), but HQ Air Combat Command wants ...
References
External links
Frequency allocation information, mostly for U.S.Spectrum allocation chart
{{Audio broadcasting
Microwave bands
Satellite broadcasting