The S-band portion of the microwave band of the electromagnetic spectrum ranges from 2.0 to 4.0 GHz., crossing the boundary between UHF and SHF at 3.0 GHz. The S-band wavelength is around 10 cm. The maritime industry shares S-band radar with other entities permitted by the Federal Communications Commission (FCC) in this country and by the International Telecommunication Union (ITU) worldwide; and this permission is granted to such entities as weather services, police and fire departments. Communications are operated by such as Digital Audio Radio Satellite (DARS) are also users of a portion of the S-band (and broadcasts in the S-band around 2.3 GHz), and is currently used by Sirius Satellite Radio and XM Satellite Radio. More recently, the FCC has approved for portions of the S-band between 2.0 and 2.2 GHz the creation of Mobile Satellite Services (MSS) networks in connection with Ancillary Terrestrial Components (ACN). The maritime industry uses a pulse-type system for maximum transmission of a signal since a steady transmission such as that used by communication sis not necessary.
This allows more efficient use of the power needs for a signal to go out and return to the unit. The advantages of S-band for the maritime industry include the ability to send a signal as far away as 48 nautical miles and receive it with dependable return. This wavelength is also optimum at these ranges when taking in consideration weather and solar disturbances. At ranges shorter than a few miles however, S-band radar's usefulness is hindered by its own characteristics required of it for the greater distances.
A disadvantage of S-band, albeit a small one is the size of the slotted waveguide array antenna that is associated with that system which can measure 3.6 meters across its face.
X-band is a radio frequency range designation that...