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OPEN-STRIP FERROMAGNETIC MARKER AND METHOD AND SYSTEM FOR USING SAME

  • US 3,790,945 A
  • Filed: 11/24/1971
  • Issued: 02/05/1974
  • Est. Priority Date: 03/22/1968
  • Status: Expired due to Term
First Claim
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1. A system for sensing the passage of an object through a surveillance area comprising:

  • means for generating an oscillating magnetic field in said surveillance area, an elongated thin open-stripe of ferromagnetic material for being secured to an object and having an aggregate saturation magnetic moment of about one pole-centimeter and producing at least one pulse of magnetic field having frequencies of very high order, extending up to and including the thousandth harmonic of the fundamental frequency of the oscillating magnetic field in response to a reversal of said field.

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