Electro-Magnetic Band-Gap feed overlapping apertures for multi-beam antennas on communication satellites
An `EBG antenna (Electro-Magnetic Band Gap)' is built with a semi-reflective screen over a set of horns feeding a reflector. A clever application of the partial spreading of the electro-magnetic field in such a structure is to provide `overlapped radiating apertures', which generate `overlapped beams' when feeding a reflector. This is a unique single-antenna solution, fitting with multi-beams missions from satellite which require low gain ripple over a regional coverage, e.g. for high data-rate communication in Ka-band. A prototype has been optimised and built, as a co-operation between Thales Alenia Space France & XLIM/Antenna Lab, supported by space agencies ESA & CNES. Adding a very light meanderline polariser (honeycomb based) transforms the alternated orthogonal linear polarisations into orthogonal circular ones, coping with most recent missions.