Effective shielding is essential for ensuring proper EMC performance, but measuring it correctly can be tricky. @karen.burnham recently highlighted critical concepts for measuring shielding effectiveness, offering practical advice and insights for engineers during a webinar with Sierra.
Here’s what she had to say:
- Fundamental measurement concept: Compare the energy or power picked up in unshielded versus shielded configurations. Shielding effectiveness is always a positive number—bigger is better!
- dB makes math easy: “EMC engineers love working in decibels—just kindergarten math: addition and subtraction!”
- Reverb chamber benefits:
- Covers large frequency areas quickly
- Illuminates the target from multiple angles
- Ideal for real-world simulations
However, reverb chamber testing has its limitations, especially on the lower frequency side where it struggles to provide statistically meaningful data.
Measurement methods:
Karen emphasized the importance of measuring shielding effectiveness using unshielded vs. shielded configurations of the same cable assembly instead of relying on comparisons with reference antennas, which can overstate the shielding effect.
What’s your experience with shielding effectiveness measurements? Do you have a preferred method or any tips for accurate results?
Watch the full webinar here.