The S band is part of the microwave band of the electromagnetic spectrum. It is defined by an IEEE standard for radio waves with frequencies that range from 2 to 4 GHz, crossing the conventional boundary between UHF and SHF at 3.0 GHz. The S band is used by weather radar, surface ship radar, and some communications satellites, especially those use...
A range of microwave radio frequencies in the neighborhood of 2 to 4 GHz, used for communicating with piloted space missions (~2 Ghz).
(from the article `radar`) The ASR-9 system operates at frequencies from 2.7 to 2.9 GHz (within the S band). Its klystron transmitter has a peak power of 1.3 megawatts, a pulse ...
A range of microwave radio frequencies in the neighborhood of 2 to 4 GHz. 
The S-band is the frequency band from 1550 to 5200 Mhz employed in radar.
A band of radio frequencies extending from 1550 to 5200 MHz. See also: V-Band, X-Band.