Shielding Effectiveness
A solid metal barrier attenuates an incident field two ways: reflection at its surfaces (an impedance mismatch to the wave) and absorption as the field decays through the skin depth. This tool estimates both, and their sum — the shielding effectiveness — for a far-field plane wave, from the material, thickness and frequency. Far-field approximation; near-field (dominant-E or dominant-H source) reflection differs and depends on source distance.
Equations & Parameters ▸
\(A=1.314\,t_{mm}\sqrt{\mu_r\,\sigma_r\,f_{MHz}}\ \text{dB}\)
\(R=168+10\log_{10}\!\dfrac{\sigma_r}{\mu_r\,f_{MHz}}\ \text{dB} \qquad SE=A+R\)
\(R=168+10\log_{10}\!\dfrac{\sigma_r}{\mu_r\,f_{MHz}}\ \text{dB} \qquad SE=A+R\)
| Material | Sets relative conductivity σr and permeability µr (referred to copper). |
| t | Barrier thickness (mm). |
| f | Frequency (MHz). |
| A, R | Absorption and (plane-wave) reflection loss. Multiple-reflection correction is negligible once A > ~10 dB. |
Reference: H. W. Ott, Electromagnetic Compatibility Engineering, Wiley, 2009 (Schelkunoff shielding theory).
Inputs
σr, µr vs Cu
mm
WallMHz
BandResults
Loss terms
Absorption A—
Reflection R—
Total
Shielding effectiveness SE—
Field attenuation—
Diagram