What is X-band?
X-band covers 8–12 GHz and is the primary frequency band for military satellite communications (MILSATCOM) globally. The ITU allocates significant X-band spectrum specifically for government and military fixed and mobile satellite services, with commercial use restricted in most jurisdictions. This segregation from commercial Ku/Ka-band systems reduces interference risk and provides an inherently less congested frequency environment for military operations.
Military X-band systems
The US Department of Defense operates the Wideband Global SATCOM (WGS) constellation — 10 GEO satellites providing X-band and Ka-band military communications across all DoD combatant commands. The UK's Skynet 5 and 6 series, NATO's SATCOMBw, France's Athena-Fidus, and Italy's SICRAL all provide X-band military communications to their respective forces. NATO has a joint X-band satellite communications interoperability agreement that allows member nations' forces to use allied X-band satellite capacity, critical for combined joint operations.
Earth observation downlinks
Beyond MILSATCOM, X-band is widely used for Earth observation payload data downlinks because it offers higher bandwidth than S-band (typically 100 Mbps to 1 Gbps downlink rates) with manageable antenna sizes. Commercial imagery satellites from Maxar, Airbus, and Planet Labs use X-band for high-rate data downlinks to commercial ground stations. ESA's Sentinel-1 SAR satellite downlinks at X-band at 520 Mbps to receiving stations. The combination of military and EO use creates substantial demand in the X-band market, particularly for ground station services at polar facilities that can downlink data from multiple SSO passes per day.