Designation by the Institute of Electrical and Electronics Engineers (IEEE) for a portion of the electromagnetic spectrum in the microwave range of frequencies ranging from 4.0 to 8.0 gigahertz (GHz), however, this definition is the one used by radar manufacturers and users, not necessarily by microwave radio telecommunications users.
The C-band (4 to 8 GHz) is used for many satellite communications transmissions, some Wi-Fi devices, some cordless telephones, and some weather radar systems.
The C-band communication satellites typically have 24 radio transponders spaced 20 MHz apart, but with the adjacent transponders on opposite polarizations. Hence, the transponders on the same polarization are always 40 MHz apart. Of this 40 MHz, each transponder utilizes about 36 MHz.