An antenna including a magnetic core made of a soft-magnetic non-electro conductive material, including four corner protuberances defining two orthogonal winding channels around the magnetic core; X-winding (DX), Y-winding (DY) and Z-winding (DZ) of conductive wire orthogonal to one another wound around the magnetic core, wherein the antenna further has a first soft magnetic sheet attached superimposed on said four corner protuberances of the magnetic core providing a limiting edge for the Z-winding (DZ), so that an increase of the sensitivity of the Z-winding (DZ) and a reduced thickness of the antenna in the Z-axis (Z) direction are obtained.