Skin Depth Calculator

Calculate the skin depth (penetration depth) of electromagnetic waves in a conductor at a given frequency.

Hz
S/m

Copper = 5.8e7, Aluminum = 3.77e7

1 for non-magnetic materials

Skin Depth

0.000066 m

Skin Depth0.0661 mm
Skin Depth66.1 µm

Skin Depth vs Frequency

What is Skin Depth?

Skin depth is the distance into a conductor at which the current density drops to 1/e (about 37%) of its surface value. At high frequencies, current flows mostly near the surface.

Formula

delta = 1 / sqrt(pi x f x mu x sigma)

Where f is frequency, mu is permeability (mu_0 x mu_r), and sigma is conductivity.

Practical Impact

  • At 1 MHz in copper: skin depth is about 0.066 mm
  • At 1 GHz in copper: about 2.1 micrometers
  • Conductors for RF need only be a few skin depths thick
  • Example Calculation

    Copper conductor (sigma = 5.8e7 S/m, mu_r = 1) at 1 MHz.

    1. 01mu = 1 x 4pi x 10^-7 = 1.2566e-6 H/m
    2. 02delta = 1 / sqrt(pi x 1e6 x 1.2566e-6 x 5.8e7)
    3. 03= 1 / sqrt(229.37) = 1 / 15.15 = 0.0660 mm = 66.0 micrometers

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