An extended range coil for an inductance-capacitance tuned circuit and a method for its manufacture. The extended range coil comprises a wire-wound planar spiral portion, having a circumference, and a wire-wound wall portion joined to the wire-wound planar spiral portion and extending outward from the...http://www.google.es/patents/US6246328?utm_source=gb-gplus-sharePatente US6246328 - Extended range passive marker
