Coil assembly

A coil assembly comprising:

• a plurality of coil layers which are stacked on one another in a stacking direction, each of the coil layers including a plurality of planar coils which are wound in a planar direction perpendicular to the stacking direction and electrically connected in parallel to each other between the coil layers;
• and
• a plurality of coil units each of which includes at least one of the planar coils disposed on a respective one of the coil layers, the plurality of coil units being connected in parallel to each other, wherein
• the coil layers include a first pitch coil layer and a second coil pitch layer, the first pitch coil layer having disposed thereon wound conductive wires, two adjacent ones of which are arranged at a pitch away from each other, the second pitch coil layer having disposed thereon wound conductive wires, two adjacent ones of which are arranged at a pitch away from each other, the pitch of the first pitch coil layer being different from that of the second pitch coil layer, and
• the pitch of the first pitch coil layer is greater than the pitch of the second pitch coil layer.