Toroidal variometer for a magnetic particle imaging device

In order to gain a supremely pure high-power signal, it is necessary to use high attenuation frequency filters. For this purpose, oscillating circuits can be used. The reactive elements in each oscillating circuit have to be adjusted very precisely to each other and to the resonant frequency as well. Additionally, it has to be taken care of scattering fields and signal distortion. The presented device is an air core coil with variable inductance and low scattering fields. It does not contain any ferromagnetic material to avoid the generation of higher harmonics within the filter.