A one-dimensional magnetic field sensor comprises a support, a single elongated magnetic field concentrator or two magnetic field concentrators, which are separated by a first gap, and at least one magnetic sensor element. The magnetic field concentrator, or both thereof, consists of at least two parts which are separated from each other by second gaps. A two-dimensional magnetic field sensor comprises a support, a single magnetic field concentrator which consists of at least three parts which are separated from each other by gaps, and at least two magnetic sensor elements.