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Impedance-matching-network-and-multidimensional-electromagnetic-field-coil-for-a-transponder-interrogator

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Impedance matching network and multidimensional electromagnetic field coil for a transponder interrogator

Details

Inventors: Ward, Jr., William H.;
Assignee: Avid Identification Systems, Inc. (Norco, CA)
Primary Examiner: Crosland; Donnie L.
Assistant Examiner:
Attorney, Agent or Firm: DLA Piper US LLP

An improved interrogator for an inductively coupled identification system is disclosed. The interrogator provides a multidimensional electromagnetic field through a plurality of coils aligned relative to each other. The coils provide a rotating magnetic field having approximately constant amplitude regardless of orientation with respect to the transponder. An additional coil may be utilized to precess the multidimensional electromagnetic field. The interrogator may further provide an impedance matching network that includes a series drive capacitor to match the impedance of a capacitor in parallel with a coil to a driver load impedance.

DETAILED DESCRIPTION In accordance with the teachings of the present invention, an impedance matching network and multidimensional electromagnetic field coil for an interrogator are provided.
The improved interrogator provides a multidimensional electromagnetic field through two coils aligned preferably perpendicularly to each other.
The coils are energized so as to provide a rotating magnetic field having approximately constant amplitude regardless of its orientation with respect to the transponder.
An additional coil may be provided to precess the rotating magnetic field.
The interrogator may further provide an impedance matching network that includes a series drive capacitor to match the impedance of a capacitor in parallel with a coil (parallel resonant tank circuit) to a driver's output impedance.

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