Fundamental Operating Principles - RFID: Fundamentals and Applications in Contactless Smart Cards and Identification - page 37

Figure 3.9 Electromagnetic labels in use (reproduced by permission of Schreiner Codedruck,

Munich)

Figure 3.10 Practical design of an antenna for an article surveillance system (reproduced by
permission of METO EAS System 2200, Esselte Meto, Hirschborn)

high. The boxes contain two metal strips, a hard magnetic metal strip permanently
connected to the plastic box, plus a strip made of amorphous metal , positioned such
that it is free to vibrate mechanically (Zechbauer, 1999).
Ferromagnetic metals (nickel, iron etc.) change slightly in length in a magnetic field
under the influence of the field strength H. This effect is called magnetostriction and
results from a small change in the interatomic distance as a result of magnetisation. In