Shielding Effectiveness Calculator

Analyze reflection, absorption, and transmission with engineering inputs. Build stronger electromagnetic barriers using clearer results and smarter design choices today.

Estimate electromagnetic shielding performance from material properties, frequency, geometry, and field regime. Review reflection, absorption, and transmission losses in one place.

Calculator Inputs

Frequency (Hz)

Enter the operating frequency of the incident field.

Conductivity (S/m)

Copper is about 5.8e7 S/m for reference.

Relative Permeability

Higher values often improve magnetic attenuation.

Relative Permittivity

Used for material characterization and reporting.

Shield Thickness (mm)

Absorption rises as thickness grows beyond skin depth.

Source Distance (mm)

Important for near-field electric and magnetic estimates.

Incident Field (V/m)

Used to estimate transmitted field after shielding.

Field Regime

Choose the field condition relevant to your application.

Shielding Performance Graph

This chart sweeps frequency around the selected operating point and compares total shielding effectiveness with reflection and absorption contributions.

Formula Used

This calculator uses a practical engineering model that splits total shielding effectiveness into reflection loss, absorption loss, and a multiple-reflection correction.

Total shielding effectiveness:
SE(dB) = R + A + B

Skin depth:
δ = √[2 / (ωμσ)]

Angular frequency:
ω = 2πf

Absorption loss:
A(dB) = 8.686 × (t / δ)

Plane-wave reflection estimate:
R(dB) = 20 log10(η₀ / 4|Z_s|)

Surface impedance magnitude:
|Z_s| = √(ωμ / 2σ)

Multiple reflection correction:
B(dB) = 20 log10(|1 − e^−2t/δ|), often neglected when A ≥ 10 dB

For near-field cases, the calculator applies separate engineering estimates for electric-field and magnetic-field reflection behavior using source distance and material terms.

How to Use This Calculator

Enter the signal frequency in hertz.
Provide material conductivity, relative permeability, and relative permittivity.
Enter shield thickness in millimeters.
Set source distance for near-field evaluation.
Choose the field regime: plane wave, near-field electric, or near-field magnetic.
Enter incident field strength to estimate the transmitted field.
Press the calculate button to view the result above the form.
Review the detailed table, graph, and export the report as CSV or PDF.

Example Data Table

Material	Frequency (Hz)	Conductivity (S/m)	Relative Permeability	Thickness (mm)	Field Regime	Typical Result Trend
Copper foil	1,000,000	5.8E+07	1.0	0.5	Plane wave	Strong reflection and moderate absorption
Aluminum sheet	10,000,000	3.5E+07	1.0	1.0	Plane wave	Balanced shielding across wider frequencies
Steel enclosure	100,000	6.0E+06	100.0	2.0	Near-field magnetic	Improved low-frequency magnetic attenuation
Nickel alloy	5,000,000	1.4E+07	80.0	0.8	Near-field electric	Higher absorption with stronger mismatch

FAQs

1. What does shielding effectiveness mean?

Shielding effectiveness measures how much an enclosure or material reduces electromagnetic energy. It is usually expressed in decibels, combining reflection, absorption, and internal re-reflection effects.

2. Why is skin depth important?

Skin depth shows how deeply electromagnetic current penetrates a conductor. When shield thickness exceeds several skin depths, absorption improves and multiple-reflection effects become less important.

3. When should I use near-field magnetic mode?

Use near-field magnetic mode when the noise source is close to the shield and magnetic coupling dominates, especially at lower frequencies around transformers, motors, coils, and power electronics.

4. Does higher conductivity always improve shielding?

Higher conductivity usually improves reflection and helps reduce surface impedance, but low-frequency magnetic shielding may still need higher permeability materials or increased thickness for better performance.

5. Why can magnetic shielding be difficult at low frequencies?

Low-frequency magnetic fields penetrate common conductors more easily. Materials with higher permeability and thicker sections often work better because they guide magnetic flux and increase absorption.

6. What does a 40 dB shielding result mean?

A 40 dB shielding result means the field amplitude is reduced by about 100 times, while transmitted power is reduced by about 10,000 times under the model assumptions.

7. Why is the multiple-reflection term sometimes zero?

When absorption exceeds about 10 dB, internal reflections are usually insignificant in practical engineering calculations. The correction term is therefore often neglected to simplify interpretation.

8. Can this calculator replace laboratory testing?

No. This calculator is a design and comparison tool. Final products should still be validated with measurements because apertures, seams, coatings, cable entries, and geometry can reduce actual shielding.