Antenna and driving circuit for transmitting and receiving signals to and from a passive transponder

• US 5,420,579 A
• Filed: 12/28/1993
• Issued: 05/30/1995
• Est. Priority Date: 10/29/1990
• Status: Expired due to Term

• Current Assignee: Bio Medic Data Systems Incorporated (ATS Corp.)
• Original Assignee: Bio Medic Data Systems Incorporated (ATS Corp.)
• Inventors: Ellwood, David, Urbas, Donald J.
• Primary Examiner(s): Horabik, Michael
• Application Number:
  US08/175,475
• Time in Patent Office: 518 Days
• Field of Search: 340/870.31, 340/870.32, 340/825.54, 343/738, 343/856, 343/867, 343/792, 455/41, 455/82, 455/263, 455/273, 455/274, 455/279, 324/313, 324/314, 324/318, 324/322
• US Class Current: 340/10.34
• CPC Class Codes: G01V 15/00 Tags attached to, or associated with, an object, in order to enable detection of the object record carriers for use with machines having a detectable tag or marker G06K19/00
• CPC Class Codes: G06K 19/07779 the inductive antenna being a coil
• CPC Class Codes: H01Q 7/08 Ferrite rod or like elongated core

Abstract

A system for receiving a signal from a passive transponder includes a probe which transmits an exciter signal having a first frequency and receives a signal from the transponder having a second frequency. The probe includes an antenna for transmitting the exciter signal. The antenna includes a second coil and a primary coil wound about the second coil. The second coil is tuned to resonate at the first frequency. A receiver is provided for driving the primary coil at the first frequency.

Claims

1. A system for transmitting an exciter signal to a passive transponder and receiving a transponder signal, said system comprising receiving means for generating an exciter signal, probe means for transmitting said exciter signal to a passive transponder, said exciter signal having a first frequency, said probe means being adapted to receive said transponder signal from a transponder, said transponder signal having a second frequency, said probe means including an antenna means for transmitting said exciter signal, said antenna means including a secondary coil, secondary coil tuning means coupled to said secondary coil for maintaining said secondary coil tuned to said first frequency, a primary coil wound about said secondary coil and inductively coupled therewith, said secondary coil being tuned to resonate at said first frequency, said receiver means including coil driving means for applying said exciter signal to said primary coil so that said secondary coil resonates at said first frequency of said exciter signal to transmit said exciter signal, said exciter signal having a cycle, said primary coil driving means outputting a portion of a cycle wave at said first frequency causing said primary coil to generate a portion of a cycle of said exciter signal and said secondary coil to generate the entire cycle of said exciter signal.

2. The system for receiving a signal from a passive transponder of claim 1, wherein said secondary coil tuning means includes variable capacitor means coupled to said secondary coil for adjusting the frequency at which said secondary coil resonates.