OPEX - A New Era of Satellite Propagation Research

When ESA´s latest telecommunications satellite OLYMPUS was launched in summer of 1989 it carried a payload producing three unmodulated beacons at 12.5, 19.8 and 29.7 GHz. The main purpose of these beacons is to enable scientists to carry out long term slant path propagation experiments at these frequencies. The Olympus Propagation Experimenters group, OPEX, which was set up under ESA auspices in 1980, had been preparing for this event very carefully. The specifications for the equipment to be used and the elaboration of standard procedures for data processing and analysis have been worked out jointly. Today the OPEX community includes approximately 30 groups of experimenters. The aim of this paper is to give a short review of the accomplishments made so far and the work planned for the future.