EMC Question of the Week: November 7, 2022

An EMC Test Set-up in a Semi-anechoic chamber

The EMC test set-up in the photo is designed for measuring  

  1. CISPR 32 radiated emissions
  2. CISPR 12 radiated emissions
  3. electrostatic discharge immunity
  4. radiated immunity


The best answer is “d.” The first clue that this might be a radiated immunity test is the three-axis electric-field probe just to the right of center on the table. The probe monitors the incident electric field strength and feeds that information through an optical cable back to the test system. Of course, it's possible that somebody left the probe on the table while performing a different test, so let's examine the other choices.

CISPR 32 radiated emissions tests are also performed in a semi-anechoic environment, but they would never be done with a metal tabletop. CISPR 12 radiated emissions tests are vehicle-level tests and would not be performed on a table of any kind.

Electrostatic discharge (ESD) immunity tests can be performed on a table with a metal top. They also could be (but wouldn't need to be) performed in a semi-anechoic chamber (even one with an antenna parked nearby). However, there are no standard ESD immunity tests where the metal tabletop is grounded to the floor with wide copper straps. The tabletop would have to be connected to the floor with high-valued bleed resistors.

Of the choices presented, radiated immunity is the only standard test consistent with the set-up shown in the figure.

Have a comment or question regarding this solution? We'd like to hear from you. Email us at This email address is being protected from spambots. You need JavaScript enabled to view it..