Why Low Frequency C Band Matters In Satellite Connection

in Satellite

Ka, Ku and C bands make satellite communications possible. Capacity, frequency and wavelength differ in each band family. These factors, especially radio frequency , greatly affect the speed and thoroughput of satellite communication systems. Of all the three satellite radio bands, the one with the lowest frequency, the  C band, is the most resistant to "rain fade".

Because C-band has lower frequency and longer wavelength, it is not as prone to “rain fade” or signal attenuation as Ka and Ku bands. However, operating on relatively low  frequency means being dependent on "big ugly dishes" or satellite dishes with larger diameter.

Nevertheless, this radio band plays a vital role in tropical and subtropical markets where high frequency bands underperform. There is a high demand for C band in Asia-Pacific regions. Rural spots in rain-prone regions can support distance education,  telemedicine, emergency assistance and satellite TV programming, thanks to C band. C band is so reliable that several telecommunications regulators want to free some cable TV networks' C band frequencies to allocate them for wireless broadband and telecommunication applications.

In choosing a teleport location, climate cannot be ignored. Even a nanosecond of delay in  the 90,000 mile round-trip of satellite signals can dramatically affect speed and user experience. Moderate-to-heavy rainfall can cause a minor effect on latency, but it could result into high error rate in signal modulation and transmission, much slower thoroughput and even interruption of  broadband connection.

Radio frequencies above 1 GHz tend to be absorbed by rainfall. Electromagnetic interference also happens due to other atmospheric phenomena like snow. It is not uncommon to have signal attenuation even if the rainfall is far from the satellite dish or teleport. This may happen when the signal path crosses precipitation many miles away and when the dish is positioned with a low look angle.

Daily service interruption is common in various tropical areas served by Ka and Ku satellite providers. Rain fade is indeed one of the major drawbacks of communicating via geostationary satellites. Unlike other types of satellites, this type of satellite is located 20,000 miles above Earth, which is much higher. Such satellites need strong transceiver to penetrate through rain across various atmospheric levels.

It is generally advisable to use long C-band waves instead of shorter Ka and Ku bands. This will minimize the negative effects of rainfall. It is more cost-effective than overhauling Ka and Ku band satellite dishes to make them as large as their C-band counterpart.

Although K bands have high thorougput, satellite TV operators continue to rely on C-band . Because high frequency bands are weather dependent, satellite TV broadcasters find it risky to switch to Ka or Ku bands. Support for C band will remain stable as long as rain fade remains a problem in satellite communications.


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Ed Brown has 8 articles online

Ed keeps an eye on the latest developments in C band technology.


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Why Low Frequency C Band Matters In Satellite Connection

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Why Low Frequency C Band Matters In Satellite Connection

This article was published on 2011/12/15