The present disclosure relates to a beam forming device, comprising a transmit unit comprising at least two transmit elements that transmit radiation towards a scene, a receiver unit comprising at least two receive elements that receive radiation from said scene and that generate receive signals from said received radiation, and a beam forming unit that performs beam forming to obtain beam formed output signals from said receive signals by use of beam forming weights, wherein said beam forming weights are adapted to a distance between the scene and one or more transmit elements and/or receive elements, said distance being indicated by a distance indicator, and wherein said beam forming weights are changed if said distance changes.