Formulas & Calculations

The attenuation requirements of your specific applications drive the final design of a shield. With a given geometry, we are able to increase the performance of a shield by increasing the thickness of the material. However, if your application requires a more robust shield you can drastically increase your shielding performance by adding additional layers to your shield while maintaining an air gap between each layer.

The following formulas can help you calculate single, dual, and triple-layer shield designs. It is important to note that the value for the permeability of a material used for the purposes of a calculation depends on material composition, shield geometry, and field intensity. Our experienced technical staff is a resource and generous collaborator available to work through these design calculations with you.

Single Layer

(µ/4)(1-(Ri²/Ro²))+1

A= Attenuation @ DC
µ= Permeability value of material
RI= Inside Radius
RO= Outside Radius

Dual Layer

A= 1+S1+S2+(S1S2N12)

A= Attenuation @ DC
S1= Attenuation of inner layer (using formula above)
S2= Attenuation of outer layer (using formula above)

RO1= Outside radius of inner layer
RI2= Inside radius of outer layer

Triple Layer

A=(µ/4) * [(1-Q1Q2Q3)+(µ2/16) * (N1N12N2N23N3)+(µ/4) * (N1N3+N1N2-N1N2N3) (N12) + (N1N3+N2N3-N1N2N3)(N23)-(N1N12N2N23)]

A = Attenuation @ DC
µ = Permeability of the material
RI1 = Inside radius of innermost layer
RO1 = Outside radius of innermost layer
RI2 = Inside radius of middle layer
RO2 = Outside radius of middle layer
RI3 = Inside radius of outermost layer
RO3 = Outside radius of outermost layer
Q1=(RI1²)/(RO1²)
N1 = 1-Q1
Q12=(RO1²)/(RI2²)
N12 = 1-Q12
Q2=(RI2²)/(RO2²)
N2 = 1-Q2
Q23=(RO2²)/(RI3²)
N23 = 1-Q23
Q3=(RI3²)/(RO3²)
N3 = 1-Q3