Satellite communication systems are subject to international agreements and regulations. The International Telecommunication Union (ITU)
regulates frequency use and defines “bands”.
The following bands are commonly used:
– C-band was the first band to be used for satellite communication systems. However, when the band became overloaded (due to the same frequency being used by terrestrial microwave links) satellites were built for the next available frequency band, the Ku-band. Today C-Band also gets disturbed by wireless radio links. Interferences can get reduced by cost intensive microwave filters.
is typically used for broadcasting and 2-way Internet connections.
The C-band frequency range has one significant problem. It is the frequency region assigned to terrestrial microwave radio communication systems. There are an emerging number of these microwave systems located all over the world and they carry a large volume of commercial communications. Consequently, the VSAT
locations needed to be restricted in order to prevent interference with the terrestrial microwave communication systems. As mobile phones get used more and more in all countries, the use of C-Band in future will possibly certainly rather decrease than increase. At the current point of time, C Band nevertheless is widely used. In particular as Ku band capacity over some regions is quite limited.
Downlink: 3.7 – 4.2 GHz
Uplink: 5.9 – 6.4 GHz
Less disturbance from heavy rain fade
Needs a larger satellite dish (diameters of minimum 2-3m)
Powerful (=expensive) RF unit
More expensive hardware
Possible interference from microwave links
The Ku-band frequency range is allocated to be exclusively used by satellite communication systems, thereby eliminating the problem of interference with microwave systems. Due to higher power levels at new satellites Ku-band allows for significantly smaller earth station antennas and RF units to be installed at the VSAT location.
Downlink: 11.7 – 12.2 GHz
Uplink: 14.0 – 14.5 GHz
No interference from microwave links and other technologies
Operates with a smaller satellite dish (diameters from 0.9m) -> cheaper and more easy installation
Needs less power -> cheaper RF unit
More expensive capacity
Sensitive to heavy rain fade (significant attenuation of the signal)/possibly can be managed by appropriate dish size or transmitter power
Which solution to choose depends today from commercial and less from technical factors, as no matter what frequency band used – both technologies supply services at acceptable quality.
Commercially it is fact that hardware for C Band is significantly more expensive while the capacity is cheaper. So customers with large bandwidth requirements preferably choose this technology.
Ku Band on the other hand operates with small antennas and less expensive equipment, while the capacity price is higher than C Band.