A magnetically communicative card (200) has a ferrite core (302) extending substantially the width (201) of the card body (203) and has a conductor (408) wound around the ferrite core for the entire length of the ferrite core. Embedded within the card body is a controller (208) that controls a varying...http://www.google.es/patents/US6206293?utm_source=gb-gplus-sharePatente US6206293 - Magnetically communicative card
