The magnetron sputtering source comprises a target mount for mounting a target arrangement comprising a sputtering target having a sputtering surface; a primary magnet arrangement for generating close to said sputtering surface a magnetron magnetic field describing one tunnel-like closed loop having an arc-shaped cross-section; a secondary magnet arrangement for generating close to said sputtering surface an auxiliary magnetic field having a substantially arc-shaped cross-section, said auxiliary magnetic field superposing with said magnetron magnetic field and being substantially inversely polarized with respect to said magnetron magnetic field; and an adjustment unit for adjusting said auxiliary magnetic field. The vacuum treatment apparatus comprises such a magnetron sputtering source. The method for manufacturing coated substrates by magnetron sputtering using a magnetron sputtering source comprises the steps of a) generating close to a sputtering surface of a target said magnetron magnetic field; b) generating close to said sputtering surface said auxiliary magnetic field; and c) adjusting said auxiliary magnetic field. In particular, said secondary magnet arrangement comprises several separately adjustable segments. Using the invention, it is possible to determine gauge functions for precisely achieving target thickness distributions.