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Electronic article surveillance system

  • US 5,825,291 A
  • Filed: 03/25/1997
  • Issued: 10/20/1998
  • Est. Priority Date: 04/10/1996
  • Status: Expired due to Fees
First Claim
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1. An electronic article surveillance system for producing an alarm signal when an article of merchandise having a responder attached thereto is carried through an exit passageway, said system comprising an interrogation signal generator connected via a first pair of terminals to a transmitter antenna for generating electromagnetic waves in an interrogation zone and a receiver connected via a second pair of terminals to a receiver antenna for receiving electromagnetic waves present in said interrogation zone, said receiver including signal processing circuits for detecting predetermined characteristics in the received waves to generate an alarm, said transmitter antenna extending in a horizontal plane above said passageway and said receiver antenna extending in a horizontal plane below said passageway, each of said antennas being formed of a plurality of loops which extend over different, non-overlapping areas in a common plane and which are electrically connected in parallel to its respective pair of terminals, the loops of said receiver antenna being connected such that currents flow in parallel therein in mutually opposite directions and the loops of said transmitter antenna being connected such that currents flow in parallel;

  • therein in the same direction.

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