Ultra-Low-Cost RFID Based on Soft Magnetic Ribbons

An ultra-low-cost radio-frequency identification tag is presented comprising a soft magnetic ribbon that is biased by an adjacent permanent magnet. The tag is read by measuring changes in the ribbon’s magnetization while applying magnetic ac and dc fields. A harmonic analysis of the response signal allows us to determine both the ribbons’ soft magnetic properties and the strength of the permanent magnet. When manufacturing the tags each of these two parameters can be independently chosen out of a set of well distinguishable values. This constitutes a two-digit identification system. A set of eight different tags was demonstrated to be identifiable.