There are four Radio Frequency (RF) bands that communication and military satellites operate within:
C band – uplink 5.925-6.425 GHz, downlink 3.7-4.2 GHz
The C band is primarily used for voice and data communications as well as backhauling. Because of its weaker power it requires a larger antenna, usually above 1.8m (6ft). However, due to the lower frequency range, it performs better under adverse weather conditions on the ground.
X band – uplink 7.9- 8.4 GHz, downlink 7.25 – 7.75 GHz
The X band is used mainly for military communications and Wideband Global SATCOM (WGS) systems. With relatively few satellites in orbit in this band, there is a wider separation between adjacent satellites, making it ideal for Comms-on-the Move (COTM) applications. This band is less susceptible to rain fade than the Ku Band due to the lower frequency range, resulting in a higher performance level under adverse weather conditions.
Ku band – uplink 14 GHz, downlink 10.9-12.75 GHz
Ku (K band Under) band is used typically for consumer direct-to-home access, distance learning applications, retail and enterprise connectivity. The antenna sizes, ranging from 0.9m -1.8m (~6ft), are much smaller than C band because the higher frequency means that higher gain can be achieved with small antenna sizes than C-band. Networks in this band are more susceptible to rain fade, especially in tropical areas and ACM is used to prevent these outages.
Ka band – uplink 26.5-40GHz, downlink 18-20 GHZ
The Ka band (K band Above) is primarily used for two-way consumer broadband and military networks. Ka band dishes can be much smaller and typically range from 60cm-1.2m (2′ to 4′) in diameter. Transmission power is much greater compared to the C, X or Ku band beams. Due to the higher frequencies of this band, it can be more vulnerable to signal quality problems caused by rain fade, again ACM is used to help rain fade.