S-Band Overview.
The definition of S-band is the range of frequencies from around 1.55 ghz through to 3.9 ghz. The majority of geo-stationary satellites use s-band frequencies in one form or another. The most common use is telemetry downlink or beacons. The antenna's on the satellites for S-band are usually Omni-directional ; this is so if the satellite tumbles and the antennas no longer face the earth, commands can be sent and the satellite can be fixed.
There are other more well knows devices that transmit at s-band. These include microwave ovens on 2.450Ghz, and the new breed of wireless video-senders which also operate around the 2.4ghz mark. Other services to be found include video downlinks from police helicopters, outside broadcast events and blimp type balloons with cameras on board.