[en] A special magnet designed to saturate at 2.2 T a 2.7 mm thick, 180 mm wide and 588 mm long rectangular iron foil has been built in Saclay for the CERN SMC experiment muon beam polarimeter. It consists of an H iron yoke equipped with two magnetizing copper coils operated in a pulsed mode in order to periodically invert the foil magnetization. The operation point and the demagnetizing factor influence are discussed. The measurements with a search coil of the resulting flux density and the influence of the eddy currents are presented. The magnet fringe field which affects particle trajectories has also been measured