A frequency synthesizer device that includes two modulation paths and suitably adjusts the amplitude of a control voltage that is outputted from a digital-to-analog converter to a voltage-controlled oscillator. The device includes a series of electrodes that define an ion flow path. The inductive coupler includes a split ferrite core having material selected to provide a substantially flat frequency response between one and 50 megahertz. At least two supports are disposed along the cover edge and act in the clamping direction. The composition is used to print a field on the object, such as a stock certificate or bank note, for example.