Inmarsat - Coverage

Coverage

There are three types of coverage related to each Inmarsat satellite.

Global beam coverage

Each satellite is equipped with a single global beam that covers up to one-third of the Earth's surface, apart from the poles. Overall, global beam coverage extends from latitudes of −82 to +82 degrees regardless of longitude.

Regional spot beam coverage

Each regional beam covers a fraction of the area covered by a global beam, but collectively all of the regional beams offer virtually the same coverage as the global beams. Use of regional beams allow user terminals (also called mobile earth stations) to operate with significantly smaller antennas. Regional beams were introduced with the I-3 satellites. Each I-3 satellite provides four to six spot beams; each I-4 satellite provides 19 regional beams.

Narrow spot beam coverage

Narrow beams are offered by the three Inmarsat-4 satellites. Narrow beams vary in size, tend to be several hundred kilometers across. The narrow beams, while much smaller than the global or regional beams, are far more numerous and hence offer the same global coverage. Narrow spot beams allow yet smaller antennas and much higher data rates. They form the backbone of Inmarsat's handheld (GSPS) and broadband services (BGAN). This coverage was introduced with the I-4 satellites. Each I-4 satellite provides around 200 narrow spot beams.