Discrete Fourier coil for localization of a magnetic dipole

In this paper, we developed a new compact magnetic sensor whose size was within a rectangular parallelepiped 17 mm × 17 mm × 14 mm for two-dimensional (2D) localization of a magnetic dipole. This sensor directly measures the discrete Fourier sine and cosine coefficients of the magnetic flux density generated by a magnetic dipole. The sensor has 16 elemental coils with 78-permalloy cores which are placed along a circle with radius 5mm and connected in series, where the number of the turns of the elemental coil at angle θ is changed proportional to sinθ (cosθ) for measuring the discrete Fourier sine (cosine) coefficient. The experimental results showed that the maximum (average) localization error was 2.4 mm (0.74 mm) in a circle with diameter 200 mm.