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Antenna device of interrogator

  • US 6,963,729 B2
  • Filed: 05/30/2001
  • Issued: 11/08/2005
  • Est. Priority Date: 05/30/2000
  • Status: Expired due to Fees
First Claim
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1. An antenna device of an interrogator having a resonance frequency of a predetermined value which constitutes an automatic identification system by exchanging information with an IC tag attached to an object to be identified by electromagnetic coupling, comprising:

  • an antenna element including an antenna coil fabricated from at least one turn of an electrically conductive material, a resistance component and an inductance component connected in series with the antenna coil; and

    a capacitor which is connected in series to said antenna element with the resistance component disposed between the capacitor and the inductance component, the capacitor having a variable capacitance to maintain the resonance frequency of the antenna device at the predetermined value.

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