The disclosure relates to a method for reconstructing the source of an electromagnetic field. Firstly, a measurement space separate from the source is selected so that the measurement space is connected to the source via a magnetically homogeneous spatial region. Measured values of the electromagnetic field emitted by the source are recorded on the surface of the measurement space so that the electromagnetic field in the measurement space can be uniquely determined in the context of an error bound determined by the discreteness of the measured values. A mathematical model of the electromagnetic source is developed which has a multiplicity of unknowns, and a system of equations is set up that relates the unknowns of the model to the measured values. The system of equations is solved in order to determine the characteristics of the electromagnetic source. The disclosure also relates to an arrangement for carrying out the method.