An arrangement for influencing and/or detecting magnetic particles in a region of action, which arrangement comprises: - selection means for generating a magnetic selection field having a pattern in space of its magnetic field strength such that a first sub-zone having a low magnetic field strength and a second sub-zone having a higher magnetic field strength are formed in the region of action, - drive means for changing the position in space of the two sub-zones (301, 302) in the region of action by means of a magnetic drive field so that the magnetization of the magnetic material changes locally, said drive means comprising drive field coil units (220', 220", 220"'), - receiving means for acquiring detection signals, which detection signals depend on the magnetization in the region of action, which magnetization is influenced by the change in the position in space of the first and second sub-zone (301, 302), - drive field generator units (42, 52, 62) for generating drive signals for said drive field coil units (220', 220", 220"'), - drive signal amplifiers (41, 51, 61) for amplifying said drive signals, - coupling means coupled between said drive signal amplifiers (41, 51, 61; 422) and said drive field coil units (220', 220", 220"'), said coupling means comprising at least one tank circuit coupled to the output of said drive field amplifiers and a reactive coupling unit, coupled between the output of said at least one tank circuit and the input of the respective drive field coil unit (220', 220", 220"'), and characterised by the tank circuit comprising switched reactive elements (C 1, C 2) and by: - control means adapted to operate said at least one tank circuit at an operating frequency variable by the switched reactive elements, this operating frequency being the resonance frequency of the energy storage tank circuit. - selection means for generating a magnetic selection field having a pattern in space of its magnetic field strength such that a first sub-zone having a low magnetic field strength and a second sub-zone having a higher magnetic field strength are formed in the region of action, - drive means for changing the position in space of the two sub-zones (301, 302) in the region of action by means of a magnetic drive field so that the magnetization of the magnetic material changes locally, said drive means comprising drive field coil units (220', 220", 220"'), - receiving means for acquiring detection signals, which detection signals depend on the magnetization in the region of action, which magnetization is influenced by the change in the position in space of the first and second sub-zone (301, 302), - drive field generator units (42, 52, 62) for generating drive signals for said drive field coil units (220', 220", 220"'), - drive signal amplifiers (41, 51, 61) for amplifying said drive signals, - coupling means coupled between said drive signal amplifiers (41, 51, 61; 422) and said drive field coil units (220', 220", 220"'), said coupling means comprising at least one tank circuit coupled to the output of said drive field amplifiers and a reactive coupling unit, coupled between the output of said at least one tank circuit and the input of the respective drive field coil unit (220', 220", 220"'), and - control means adapted to operate said at least one tank circuit at an operating frequency variable by the switched reactive elements, this operating frequency being the resonance frequency of the energy storage tank circuit.