Indian Space Research Organisation

The bus is the part of the satellite that carries the payload and all its equipment into space. It is the physical platform that holds all the satellite's parts together and that provides electrical power, navigation, control and propulsion to the spacecraft. The bus also contains equipment that allows the satellite to communicate with Earth, a kind of 'remote control'.

Satellite communications spectrum

The satellite transmission bands that are of interest to us are the C-, Ku- and Ka-bands.

C-band is the oldest allocation and operates in the frequency range around 6 GHz for transmission (uplink) and between 3.7 and 4.2 GHz for reception (downlink).
Ku-band is the most common transmission format in Europe for satellite TV and uses around 14
GHz for uplink and between 10.9 and 12.75 GHz for downlink.
Ka-band uses around 30 GHz up- and between 18 and 20 GHz downlink frequency.

C-band and Ku-band are becoming congested by an increasing amount of users, so satellite service operators are more and more turning to the use of Ka-band.

The selection of the band is not something that individual service providers decide, but is rather chosen by large satellite operators based on different factors:

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Availability: C-band is still the most widely available worldwide. Ku-band is becoming more available recently in regions which were less covered in the past (South America,
Asia, Africa)

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C-band is more prone to interference from other transmission services that share the same frequencies (adjacent satellites or terrestrial transmissions) than the higher bands

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While the C-band technology is cheaper in itself, it requires larger dishes (1 to 3 m) than
Ku- and Ka-band (0.6 to 1.8 m) and therefore imposes relatively higher (installation) costs on the end-user

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Ku- and especially Ka-band make better use of satellite capacity

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Higher frequency bands (Ku- and especially Ka-) suffer significantly more from signal