| abstract |
A magnetic tag or marker is described which is capable of functioning as a multi-bit information carrying tag. The tag may be attached to an article and then used as a means of identifying that article, generally as it enters or is positioned within an interrogation zone. The tag comprises (a) a first magnetic material characterised by high permeability, low coercivity and a non-linear B-H characteristic; and (b) a second magnetic material which is capable of being permanently magnetised, the second magnetic material being magnetised with a non-uniform field pattern (A, B, C). Detection systems for use with such tags, and write/read system using them, are also disclosed. |