Testing & troubleshooting

EM shielding measurement testing and troubleshooting
EM shielding measurement testing and troubleshooting
EM shielding testing and troubleshooting equipment

EMI Shielding Effectiveness Measurement

Holland Shielding Systems measures, documents and verifies the shielding performance of Faraday cages, shielded rooms and other EMI/RFI shielding systems. The measurement compares the reference signal level without shielding with the measured signal level after shielding. The difference is expressed as shielding effectiveness in dB.

Measurement procedure
Reference measurement

The signal level is measured without shielding to establish the reference level.

Shielding measurement

The measurement is repeated with the shielding system in place.

Calculation

Reference level minus shielded level equals shielding effectiveness in dB.

Measurement points

Measurements are repeated at selected locations to identify possible weak points.

Shielding effectiveness calculation

Reference level - shielded level = shielding effectiveness.

Example: +10 dB - (-80 dB) = 90 dB shielding effectiveness.

Typical measurement locations
Shielded doors

Door leaves, frames, hinges and conductive contact surfaces are common measurement locations.

Ventilation panels

Honeycomb ventilation panels and conductive connections can be checked for electromagnetic leakage.

Filters

Power filters and signal filters can be verified to ensure they maintain the required shielding performance.

Different walls

Measurements can be performed on multiple walls to identify local variations in shielding performance.

Different heights

Testing at different heights helps verify shielding effectiveness throughout the complete enclosure.

Waveguides

Waveguides below cutoff are tested to verify they maintain the required shielding effectiveness.

Test setup and measurement method
1. Documented test setup

The complete test setup is documented so the shielding effectiveness measurement remains traceable and repeatable.

  • Distance between transmitter and receiver
  • Transmitter and receiver height
  • Position inside or outside the shielded room
  • Antenna orientation
  • Cable dimensions and routing
  • Selected measurement locations

The documented setup makes it possible to repeat measurements under comparable conditions.

2. Measurement equipment

Typical equipment used during shielding effectiveness measurements.

Transmit antenna
Signal generator
Power amplifier
Measurement software
Receive antenna
Spectrum analyzer
Coax cables
3. Test plan before measurement

Before testing, Holland Shielding Systems prepares a measurement plan based on the shielding system and required performance.

  • Description of the test object
  • Equipment list
  • Test setup
  • Measurement procedure
  • Frequency plan
  • Measurement locations
  • Acceptance criteria

Minimum pass or fail requirements are agreed with the customer before the measurement starts.

 
Holland Shielding Systems measurement approach
Multiple frequencies

Multiple frequencies can be measured within each selected frequency band.

Moving average

A moving average can reduce isolated peaks and dips in the measured data.

Documented results

The measurement setup, results and observations can be included in a test report.

Moving-average calculation

A moving average of three consecutive measured values can be used to provide a more stable interpretation of the data.

Measured values Calculation Result
1, 2, 3 → Average First moving-average value
2, 3, 4 → Average Second moving-average value
3, 4, 5 → Average Third moving-average value

This method can smooth isolated peaks and dips without removing all measurement uncertainty.

Result comparison

Measurement graphs can compare recommended test frequencies, additional HSS measurement frequencies and the calculated moving average.

Graph line Meaning
Red line Recommended measurement frequencies
Black line Moving average frequencies
Green line IEEE recommended frequencies

Measuring additional frequencies can provide a more detailed view of the shielding performance across the selected frequency range.

EMI shielding effectiveness measurement Based on IEEE 299-2006 - Annex 2

Please note: These values are measured under laboratory conditions. Results may vary in other situations; please read our Guarantee

EMI shielding test report
Report contents

After the measurement, Holland Shielding Systems can provide a test report containing:

  • General project information
  • Description of the shielded room or enclosure
  • Documented test setup
  • Measurement equipment
  • Measurement locations
  • Measured shielding effectiveness
  • Observations and conclusion
  • Engineer identification and signature

The report can support quality control, project verification and customer acceptance.

EMI shielding measurement testing and troubleshooting
Frequently asked questions
What does shielding effectiveness in dB mean?

Shielding effectiveness describes the reduction between the reference signal level and the signal level measured with the shielding system in place.

Which parts of a shielded room can be measured?

Measurements can be performed near doors, ventilation panels, filters, waveguides, cable entries, walls, ceilings and other relevant construction details.

Can the measurement method be adapted to the project?

The frequency range, equipment, measurement locations and acceptance criteria can be selected according to the shielding system and customer requirements.

Does a successful measurement guarantee complete shielding?

No shielding system provides complete shielding under all conditions. The measurement verifies the achieved reduction within the agreed frequency range, setup and acceptance criteria.

Can Holland Shielding Systems provide a test report?

A measurement report can be provided with the documented setup, equipment, measured results, observations and conclusion.

EMI Shielding Effectiveness Measurement folder

View the folder based on IEEE 299-2006.

View PDF →

Request a shielding measurement

Contact our specialists for a suitable test plan, acceptance measurement or verification of an installed EMI/RFI shielding system.

Contact Specialist →

More results