Figure 10.

(a,b) The mutual inductance was measured on a grid of $7\times 7$ points at 10 $\mathrm{cm}$ and 20 $\mathrm{cm}$ from the planar field generator, for two sensor orientations: pitch angle $\theta =0^{\circ }$ and $\theta ={30}^{\circ }$. At every test point, the eight mutual inductances between the sensor coil and the eight transmitter coils are considered, leading to a total of $49\times 4\times 8=1568$ mutual inductances experimentally evaluated.