The device has a large applicator with a magnetic yoke and opposing pole shoes separated by a field gap. Magnetic coils generate a homogenous alternating magnetic field of certain field strength in the gap. A biological tissue applied with the field is brought into the gap as a target field application volume. A field concentrator e.g. ferrite, is arranged near the tissue as the volume in the gap, on or in a patient near a body part e.g. diseased prostate (23), to have the field. The concentrator concentrates the magnetic field in the target volume and locally amplifies the field.
