N 26-97 - Paris, 29 August 1997
One of the key objectives of ESA internal and external R & D is to enhance the ability of the European space industry to compete on world markets and this has borne fruit in the case of the INMARSAT 3 communication satellite series, for which European industry won the payload procurement contract.
Matra Marconi Space has delivered five communication payloads to Lockheed Martin for the INMARSAT 3 series of satellites, four of which have been successfully launched since April 1996, the last on 3 June 1997 from Kourou by an Ariane 44L launcher, (Flight 97).
These payloads generate a set of L-Band spot beams for worldwide voice and data communication services to mobile terminals as small as pocket-size messaging units on ships, aircraft and vehicles, using the latest spot-beam technology providing power-efficient dynamic allocation of communication traffic to beams and allowing greater re-use of the available spectrum.
The efficient spot-beam technology has a novel antenna front-end, invented at the European Space Agency's technical centre, ESTEC in Noordwijk (the Netherlands), by Dr Antoine Roederer, and licensed by ESA to Matra Marconi Space.
With this semi active antenna architecture invented by Dr Roederer, the excitations of the radiators feeding the reflector can be varied so as to reconfigure the spot beam coverage, while keeping the power at the level of the power amplifiers as good as constant. This results in optimum DC to RF power efficiency for the payload, maximising channel capacity for the satellites.
According to INMARSAT the operational in-flight performance of the antenna has exceeded expectations.
The novel semi-active antenna technology has now been recognised as being outstandingly efficient, in both flexibility and power consumption, and is being adopted worldwide for use in the next generation of geostationary personal communication satellites.