A magnetron assembly including one or more magnetrons each forming a closed plasma loop on the sputtering face of the target. The target may include multiple strip targets on which respective strip magnetrons roll and are partially supported on a common support plate through a spring mechanism. The strip magnetron may be a two-level folded magnetron in which each magnetron forms a folded plasma loop extending between lateral sides of the strip target and its ends meet in the middle of the target. The magnets forming the magnetron may be arranged in a pattern having generally uniform straight portions joined by curved portion in which extra magnet positions are available near the corners to steer the plasma track. Multiple magnetrons, possibly flexible, may be resiliently supported on a scanned support plate and individually partially supported by rollers on the back of one or more targets.