EMC Question of the Week: December 17, 2018

Illustration of a Cable Transfer Impedance Measurement

Which of the following cable transfer impedance measurements corresponds to the cable with the best shielding?

  1. 1 mΩ
  2. 10 MΩ
  3. 0 dB
  4. 100 dB

Answer

The correct answer is "a". Cable transfer impedance measurements are made by sending a current on the shield of a cable and measuring the voltage induced in the shielded signal wires. The transfer impedance is the ratio of the measured voltage to the shield current. The units are units of impedance and lower values represent better shielding. 

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