PARIS — Mobile satellite communications startup OverHorizon of Sweden has selected ThalesAlenia Space of France and Italy, and Orbital Sciences of Dulles, Va., to build its first satellite, to be launched in early 2012 under a contract announced by the manufacturers Dec. 23, 2009.

Based in Solna, Sweden, with offices in Arlington, Va., OverHorizon AB has declined to disclose details about its satellite’s orbital slot, frequency plan, frequency-coordination status and financing. Company officials did not immediately respond to requests for comment on their program Dec. 23.

In a November presentation to a military satellite telecommunications forum, OverHorizon said its first satellite would carry four steerable antennas and have 250 megahertz of regenerative capacity — meaning transmissions can be passed from beam to beam through on-board processing — and 250 megahertz of standard bent-pipe capacity.

Government officials in Cyprus have said OverHorizon has been given access to a Cyprus-registered orbital slot, but it remains unclear whether the satellite’s proposed frequencies have been coordinated with neighboring spacecraft.

One industry official said OverHorizon will broadcast on a little-used section of the Ku-band portion of the radio spectrum to avoid frequency-priority issues with nearby satellites using the more standard sections of Ku-band.

Each of the planned satellite’s four steerable beams will have a footprint 1,440 kilometers in diameter providing for mobile communications at rates of more than 4 megabits per second on the uplink. The satellite will also have a global beam for low-rate communications, according to the OverHorizon presentation.

ThalesAlenia Space said it would provide the OverHorizon satellite’s electronics payload, which the manufacturer said features a novel regenerative on-board signal processor. Orbital Sciences will provide the satellite’s platform, a Star 2.3 frame.

Peter B. de Selding was the Paris bureau chief for SpaceNews.