Security Tag Systems, Inc.

William D Thomas

Lucian G Ferguson

The tag includes an active strip of magnetic material that, when in the presence of a magnetic bias field within a predetermined magnetic field intensity range, responds to excitation by electromagnetic radiation of a first predetermined frequency by radiating electromagnetic radiation of a second predetermined frequency that is a frequency-divided quotient of the first predetermined frequency; and a pair of bias strips of magnetic material disposed in relation to the active strip in a common housing with the active strip for magnetically biasing the active strip with a magnetic bias field within the predetermined magnetic field intensity range. The bias strips are cut from an extruded magnetic material ribbon having a width less than the length of the active strip and a magnetic moment parallel to the lateral dimension of the ribbon. The bias strips are cut at an oblique angle to the lateral dimension of the ribbon so that each bias strip has an oblique magnetic moment having longitudinal and lateral components. The bias strips are disposed in the housing such that their respective longitudinal components have the same orientation and their respective lateral components oppose each other. The active strip is disposed in a cavity for vibration. The cavity walls are coated with a permanent anti-static material to prevent the active strip from being attracted thereto. In one embodiment, a first set of an active strip and a pair of bias strips is disposed perpendicular to a second set of an active strip and a pair of bias strips.

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St. Petersburg, FL, United States of America

William D Thomas