C band (IEEE)
The unused 4.0 MHz between the pairs of transponders act as guard bands for the likely case of imperfections in the microwave electronics.
Typical antenna sizes on C-band-capable systems range from 6 to 12 feet (1.8 to 3.5 meters) on consumer satellite dishes, although larger ones also can be used.
[4] Rain fade – the collective name for the negative effects of adverse weather conditions on transmission – is mostly a consequence of precipitation and moisture in the air.
In response to a Notice of Proposed Rulemaking of July 2018 from the US Federal Communications Commission (FCC) to make the 3.7 to 4.2 GHz spectrum available for next-generation terrestrial fixed and mobile broadband services,[5] the C-Band Alliance (CBA) was established in September 2018 by the four satellite operators—Intelsat, SES, Eutelsat and Telesat—that provide the majority of C-band satellite services in the US, including media distribution reaching 100 million US households.
The consortium made a proposal to the FCC to act as a facilitator for the clearing and repurposing of a 200 MHz portion of C-band spectrum to accelerate the deployment of next generation 5G services, while protecting incumbent users and their content distribution and data networks in the US from potential interference.
[9] One of the major members of the C-Band Alliance, Intelsat, filed for bankruptcy on 14 May 2020, just before the new 5G spectrum auctions were to take place, with over US$15 billion in total debt.
[11] Slight variations in the assignments of C-band frequencies have been approved for use in various parts of the world, depending on their locations in the three ITU radio regions.
The band 4.2–4.4 GHz is currently allocated to the aeronautical radionavigation service (ARNS) on a primary worldwide basis.
5.438 notes specifically that this band is reserved exclusively for radar altimeter installed on board aircraft and for the associated transponders on the ground.
In December 2021, Boeing and Airbus called on the US government to delay the rollout of new 5G phone service that uses C band due to concern of the interference with some sensitive aircraft instruments, especially radio altimeters operating at 4.2–4.4 GHz.
