Optimized coil design for magnetic local positioning systems

Wireless identification and locating systems are increasingly employed in retail, transportation and logistic applications. Because of the potential for low cost manufacturing and mechanical flexibility, transponders and RFID tags based on organic electronic are currently hot topics of intense research in order to replace expensive semiconductor circuits. However, despite major advances in this area, the operating frequency of organic circuit is still limited to the MHz range. Thus, in order to enable locatable organic transponders, advanced magnetic or RF locating concepts as well as strategies for optimized transponder designs are needed. In this paper two essential, yet easy to use optimization criterias for TX- and RX-coil design applicable to magnetic positioning systems are derived and evaluated. An exemplary credit-card-sized planar TX-coil and a circular RX-coil are constructed, simulated and implemented. The simulation results are compared to measured values, to verify the design approach. It is shown, that the optimized coils allow for a reading range of about 10 m.