A system for generating a magnetic field for excitation of a leadless marker assembly. The system of at least one embodiment includes a source generator that generates a plurality of alternating electrical signals each having an independently adjustable phase. A plurality of excitation coils are configured...http://www.google.com/patents/US7696876?utm_source=gb-gplus-sharePatent US7696876 - System for spatially adjustable excitation of leadless miniature marker
