Abstract: A device for coating substrates has a rectangular magnetron cathode 2 with a target, a substrate holder 16 that can be rotated around a rotating axis 17 which is parallel to the longitudinal edges of the target, a planar wall 20 made of a non-magnetic material and having longitudinal edges 21, 22 also parallel to the rotating axis 17. Behind the wall there is a magnet arrangement and the magnetron cathode 2 and the wall 20 are disposed on opposite sides of the rotating axis. The device further includes a planar anode. In order to intensify and the effect of the plasma and render it more uniform, the distance on the substrate path between the longitudinal edges 12, 13 of the target and the longitudinal edges 21, 22 of the wall parallel thereto is reduced by at least one additional wall 25, 26 with a magnet arrangement 27, 28 disposed therebehind.