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.