Antenna design for ARCHIMEDES DAB mission: an auto-compensated approach

After the frequency allocation of a slice of the L-band for Direct Audio Broadcasting (DAB) services at the latest WARC-92 in region 2, an operational system is being studied at ESTEC under the ARCHIMEDES (Advanced Research in Communications using Highly Inclined orbits for Mobile applications and other Experiments and Demonstrations using European Satellites) program. To be effective in offering a service to the European and optionally also other regions, a multi-regional highly-elliptical orbit (M-HEO) has been selected for the system. Considering the path loss variations for the 8-hour, 6-satellites constellation, it is possible to design an antenna to provide constant coverage throughout the active arc without the need for zooming of the antenna. Two different antenna designs, a phased array antenna and a scanning semi-active multimatrix antenna, were proposed and carried out for the mission.<>