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Process control instrument intrinsic safety barrier

  • US 6,980,174 B2
  • Filed: 09/30/2003
  • Issued: 12/27/2005
  • Est. Priority Date: 09/30/2002
  • Status: Active Grant
First Claim
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1. A process control instrument comprising:

  • a circuit board having first and second sides and a control circuit on the first side for generating or receiving a high frequency signal;

    an antenna including a coxial electrical conductor having a center conductor and a sheild; and

    an intrinsic safety circuit coupling the control circuit to the antenna comprising the circuit board first side including a first microstrip stub electrically connected to the control circuit and a ground plane proximate the first microstrip stub, the circuit board second side including a second microstrip stub, directly underlying the first microstrip stub, electrically connected to the center conductor, and a ground pad, underlying the ground plane, electrically connected to the shield.

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