Sband

S-band is a designation for a portion of the microwave radio spectrum generally defined as frequencies from about 2 to 4 GHz. The exact boundaries and allocations vary by regulatory authority, but the band sits between L-band and C-band in the common ITU/IEEE scheme. The term arises from the band-letter naming system used for spectrum management.

The S-band supports a variety of radar and communications applications. It is widely used for weather radar, where Doppler weather radars typically operate in the vicinity of 2.7 to 2.9 GHz. It is also used for certain satellite communications links, including space-to-Earth and Earth-to-space paths, and has been employed by military and civil radar systems. In terrestrial communications, portions of the S-band have historically supported point-to-point microwave links and, in some regions, other wireless services. Amateur radio also uses parts of the S-band, notably around 2.3 to 2.45 GHz in the 13-centimeter band.

Technically, wavelengths in the S-band range from about 15 centimeters at 2 GHz down to about 7.5 centimeters at 4 GHz. The band offers a balance of manageable antenna sizes, reasonable atmospheric attenuation, and relatively good range for radar and long-distance communications. However, the overlap with the widely used 2.4 GHz ISM band can lead to interference concerns in shared environments.

Notable uses include weather surveillance systems such as NEXRAD and historical spaceflight comms where S-band links were employed. See also C-band, X-band, Ku-band, and Ka-band for related microwave ranges.