Ku band
This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these template messages)
|
Frequency range | 12–18 cm |
---|---|
Related bands | (ITU) |
Radio bands | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
ITU | ||||||||||||
|
||||||||||||
EU / NATO / US ECM | ||||||||||||
IEEE | ||||||||||||
Other TV and radio | ||||||||||||
The Ku band (
Ku band is primarily used for
Some frequencies in this radio band are employed in
Segments and regions
America
Segments in most of North and South America are represented by
The 12.2 to 12.7 GHz (LOF 11.25 to 11.75 GHz) segment is allocated to the BSS (
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 (
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.[5]
Indonesia
The ITU has categorized Indonesia as Region P, countries with very high rain precipitation. This statement has made many people unsure about using Ku-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.
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 Ku-band can be applied in Indonesia.
Use of the Ku-band for satellite communications in tropical regions like Indonesia is becoming more frequent. Several satellites above Indonesia have Ku-band
Others
Other ITU allocations have been made within the Ku 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, Ku 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.[6][page needed] 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
The Ku band also offers a user more flexibility. A smaller dish size and a Ku band system's freedom from terrestrial operations simplifies finding a suitable dish site. For the end users Ku band is generally cheaper and enables smaller antennas (both because of the higher frequency and a more focused beam).[7] Ku band is also less vulnerable to rain fade than the Ka band frequency spectrum.
Disadvantages
There are, however, some disadvantages of the Ku band system. Around 10 GHz is the absorption peak due to orientation relaxation of molecules in liquid water.[8] Above 10 GHz, Mie scattering takes over. The effect is a noticeable degradation, commonly known as rain fade, during heavy rain (100 mm/h).[9] This problem can be mitigated by transmitting a higher powered signal from the satellite to compensate. Therefore, the Ku 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 Ku 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 Ku 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
References
- ^ IEEE Std 521 - 2002 URL only available to IEEE members
- ^ Note that in the band 11.2–12 GHz the working definitions of Ku band and X band overlap; satellite communications engineers would generally regard frequencies above 11.2 GHz as being part of the Ku band.
- ^ "SpaceX seeks FCC permission for operating all first-gen Starlink in lower orbit". SpaceNews.com. 2020-04-21. Retrieved 2020-04-23.
- ^ Radar Detectors Glossary
- ^ "Radiocommunications (Communication with Space Object) Class Licence 1998". Federal Register of Legislation. Australian Government. 2012-03-21. Retrieved 2016-07-06.
- ISBN 978-0240805863.
- ^ Satellite Communications: Advantage and Disadvantages Archived 2007-10-23 at the Wayback Machine
- ^ Martin Chaplin: Water and Microwaves Archived 2019-07-29 at the Wayback Machine.
- ^ TECH-FAQ: Ku band.