WHY A COST PROJECT ON ACTIVE ANTENNAS ?

Active Antennas for Mobile Communications

With the explosion of mobile communications and the limited resources in frequency spectrum, more sophisticated antennas are required for the "base stations" both on the ground for the cellular system and in space low earth orbits (LEO), intermediate circular orbits (ICO), geostationary earth orbit (GEO), and highly elliptical orbits (HEO).

Fig.3 Outline of ESA's EMSS mobile communication system. The ARTEMIS satellite uses a new semi-active multibeam antenna developed during COST project 245.

Fig.3 shows a block diagram of the next generation European Mobile Satellite Service (EMSS) for communications with lorries on the European continent and neighbouring regions.

The first payload for this ESA mission, which will provide 400 telephone lines, was successfully launched in 1996. It will be followed by a more powerful satellite ARTEMIS, with 3 spot beams for 800 telephone lines, using the novel antenna concept of multimatrix antennas, initially conceived and patented within the COST projects 223 and 245 and now adopted worldwide.

Here again sophisticated active antennas are required on the satellite to focus the power towards the users and to ensure best use of the frequency spectrum.

On the mobiles, special antennas, tracking the satellites all the time, are also required and have been developed during COST Project 245.

Similarly, cellular communication base stations of future generation will use active or semi-active antennas to cover more users more efficiently with the same frequency spectrum.

COST-245 Summary report

- 5 -

Mars 1997 Content Responsible : Technical Manager : Webmaster@lema.epfl.ch