The work described has been carried out on the European programme for an Airborne Multi-role, Solid-state Active array radar (AMSAR) undertaken by the GEC Thomson Dasa Airborne Radar EEIG (GTDAR) under contract to the French authorities acting on behalf of the French, German and United Kingdom Ministries of Defence. This paper describes work undertaken by the three industrial members of GTDAR, Thomson-CSF Radars and Contre-Mesures, GEC Marconi Avionics and Daimler-Benz Aerospace/Sensor Systems. An outline is presented of the architecture and predicted performance of the projected demonstrator antenna.