An array antenna comprising: a plurality of three-dimensional radiator elements (1, 22, 23, 24, 25, 26, 27), each three-dimensional radiator element comprising a plurality of conductive sidewalls and a conductive radiating top surface perpendicular to the plurality of sidewalls, the radiating top surface including a radiating patch antenna which is configured to transmit or receive electromagnetic waves; the three-dimensional radiator elements being so arranged that their radiating top surfaces are in a same plane and that at least one pair of adjacent three-dimensional radiator elements are separated by a dielectric gap, the dielectric gap forming a waveguide which in operation induces by a coupling effect electromagnetic interferences with the waves, said at least one pair of adjacent three-dimensional radiator elements having each at their opposed sidewalls facing the gap at least one of a rounded groove and a concavely-dug corner edge, the antenna comprising means (2, 3, 4, 5, 6, 7) inserted in the gap at a location where grooves and/or concavely-dug corner edges face each other to establish a galvanic contact between said at least one pair of adjacent three-dimensional radiator elements, so as to suppress the coupling effect, characterized in that said means comprise a metallic cylinder topped by a conductive head and longitudinally cut by slots (34, 35, 36, 37) so as to form a resilient cylindrical body, the resilient cylindrical body being inserted in the gap at said location where grooves and/or dug edges face each other, the conductive head being in contact with the conductive radiating top surfaces of said at least one pair of adjacent three-dimensional radiator elements, said metallic cylinder being configured to suppress the coupling effect while allowing for a thermal expansion of the adjacent three-dimensional radiator elements. a plurality of three-dimensional radiator elements (1, 22, 23, 24, 25, 26, 27), each three-dimensional radiator element comprising a plurality of conductive sidewalls and a conductive radiating top surface perpendicular to the plurality of sidewalls, the radiating top surface including a radiating patch antenna which is configured to transmit or receive electromagnetic waves; the three-dimensional radiator elements being so arranged that their radiating top surfaces are in a same plane and that at least one pair of adjacent three-dimensional radiator elements are separated by a dielectric gap, the dielectric gap forming a waveguide which in operation induces by a coupling effect electromagnetic interferences with the waves, said at least one pair of adjacent three-dimensional radiator elements having each at their opposed sidewalls facing the gap at least one of a rounded groove and a concavely-dug corner edge, the antenna comprising means (2, 3, 4, 5, 6, 7) inserted in the gap at a location where grooves and/or concavely-dug corner edges face each other to establish a galvanic contact between said at least one pair of adjacent three-dimensional radiator elements, so as to suppress the coupling effect, characterized in that said means comprise a metallic cylinder topped by a conductive head and longitudinally cut by slots (34, 35, 36, 37) so as to form a resilient cylindrical body, the resilient cylindrical body being inserted in the gap at said location where grooves and/or dug edges face each other, the conductive head being in contact with the conductive radiating top surfaces of said at least one pair of adjacent three-dimensional radiator elements, said metallic cylinder being configured to suppress the coupling effect while allowing for a thermal expansion of the adjacent three-dimensional radiator elements.