Single sided magnetic data tag reader

摘要

A magnetic data tag has a plurality of magnetic layers or elements each exhibiting a directional response to an applied magnetic field. The relative orientations of the directional responses defines the data stored in the tag. The layers may be overlapped to form a stack or placed on separate regions of a substrate. The angular orientations between adjacent layers may form a predetermined progression such as a logarithmic progression. A number of 2D and 3D magnetic readers are described in detail, one of which is single sided. The readers generate a rotating interrogating field and determine the orientation of the tag. Balanced receive coil pairs may be used such that no net emf is induced across the coil pairs. The transmit coils may be configured as thin flat solenoids.