A beam forming device and method as well as to a beam steering device and method are described. The imaging beam forming device comprises a wideband transmit unit comprising at least one transmit antenna, a receiver unit comprising at least two receive antennas and at least one receive element 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 form a receive beam and obtain beam formed output signals from said receive signals by use of beam forming weights. For different samples or groups of subsequent samples of a receive signal, a sample representing said receive signal at a different frequency, a frequency-dependent weight is used for beam forming, which frequency-dependent weights are adapted to result in a predetermined shape of said receive beam.