FREQUENCY-DIVIDING-TRANSPONDER TAG

摘要

FREQUENCY-DIVIDING-TRANSPONDER TAG A frequency-dividing transponder 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 dis-posed 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 predeter-mined magnetic field intensity range. The bias strips are formed from extruded magnetic material having a high coercivity of at least approximately 1530 oersteds and a high retentivity (remanence) of at least approximately 1970 gauss. The bias strips are cut from an extruded magnetic material ribbon having a width less than the given length of the active strip and a magnetic moment parallel to the lateral dimension of the ribbon, with the bias strips being 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; wherein the bias strips are disposed in the housing such that their respective longitudinal components aid each other and their respective lateral components oppose each other. The housing includes a cavity in which the active strip is disposed for vibration, with the cavity having walls that are coated with a permanent anti-static material to prevent the active strip from being attracted to the walls. Another embodiment of the tag includes a first set of said active strip and said pair of bias strips and a second set of said active strip and said pair of bias strips, wherein the first set is disposed in the same housing as the second set, with the active strip and the bias strips of the first set being perpendicular to the active strip and the bias strips of the second set.