Importance

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Abstract

A multiplexing arrangement for an electronic article surveillance and identification system interconnects a transmitter and a plurality of antennas. The transmitter has first and second terminals and each of the antennas includes an antenna coil. The multiplexing arrangement includes a step down transformer that has a primary winding connected across the first and second terminals of the transmitter, and also has a second winding. A first winding is positioned for inductively coupling with the antenna coil of a first antenna and a second winding is positioned for inductively coupling with the antenna coil of a second antenna. The multiplexing arrangement also includes a first switch and wiring that forms a series loop connection including the first winding, the second winding, the first switch and the secondary winding of the transformer. The first switch is arranged to selectively open-circuit the series loop connection. Also included in the multiplexing arrangement are a second switch connected across the second winding for selectively short-circuiting the second winding and a third switch connected across the first winding for selectively short-circuiting the first winding. The first, second and third switches may be implemented using MOSFETs that are completely isolated from the transmitter.

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First Claim