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EMC⁄EMI Measurement Service

AET, Inc. offers you the reliable EMC/EMI measurement services (Near-field and Far-field measurements).

EMC ⁄ EMI Measurement EMC ⁄ EMI Measurement

Near-field Measurement

Near-field measurement ( < 18GHz) using high-resolution magnetic field probe

Far-field Measurement

Provided by the partner company.

    Measurement Facilities
  • 3m, 10m far-field measurements --- anechoic chamber, shielded room
  • 10m anechoic chamber
  • 3m anechoic chamber
  • Small anechoic chamber (for noise cancellation of defense⁄aircraft equipment)
  • Shielded room (for EMC test, surge test, power pulse test)
  • Other test equipment corresponding to VCCI, FCC, CE, MIL and JASO

Near-field EMI measurement example

Electromagnetic Field Measuring Equipment
Electromagnetic Field Measuring Equipment
Magnetic Field Probe
Magnetic Field Probe

To compare the noise of a multi-layer substrate (100mm x 100 mm) with and without 5 bypass condensers, the near-field electromagnetic distribution is measured using the magnetic field probe.

Measurement System

  • Electromagnetic Field Measurement Equipment: 4EM500 (NEC)
  • DUT: Multilayer substrate (100 mm × 100 mm) equipped with DSP and the memory
  • Measurement Frequency: 10MHz ~ 998MHz
  • Magnetic Field Probe: MP-10L (or equivalent)
  • Measurement Points: 100 × 100, 0.5mm pitch

Magnetic Probe Method (MP Method)

The MP method defined in IEC61967 is a means of evaluating EMI noise by non-contact current measurement of the module's power supply using the magnetic probe.

Measurement Result

Multi-layer substrate (100mm × 100mm)
(Results with and without bypass capacitors, C13 to C17)

(1) Measurement at the DSP Ο point (peak at 29.75 MHz)
The magnetic field is strongest at the DSP output area. The magnetic field is spreading out into the I/O area. Almost no effect by the bypass capacitor can be seen.
(2) Measurement at the flash memory Ο point (peak at 266.76 MHz)
The effect of the memory area bypass capacitor can be seen, but the magnetic field has spread into the I ⁄ O area.
(3) Measurement at the right end of substrate Ο point (peak at 844.46 MHz)
Almost the entire board has magnetic field. The effectiveness of the bypass capacitor cannot be seen.

Bypass capacitors are used to stabilize the power supply and suppress the noise, but as can be seen above, in the 10MHz-998MHz range, there is no considerable effect provided by the bypass capacitor. For effective decoupling, the capacity, amount, positioning, and type of capacitor should be taken account and verification via a standardized method is essential. In AET, we provide the near-field EMI measurements per module using magnetic field probes. Please allow us to minimize your EMI costs by providing you with the optimum design approach.

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