Abstract: The present invention concerns an antenna system (100) intended to be embarked on an aircraft, comprising a phase-control array antenna (110) made up of a plurality of polarization-controlled elementary antennas (120), connected to at least one beamformer (151, 152), comprising: a calculator (160) adapted to calculate phase offset values (?V, ?H) and attenuation coefficients (?V, ?H) from position and attitude information of the aircraft, coordinates of a telecommunications satellite and polarization characteristics of a transponder of said satellite; a polarization control means (130) using said phase offset values and the attenuation coefficients to control the polarization of said elementary antennas.