Skin Effects in Straight Wires
Skin Effects in Straight Wires
A wire carrying high-frequency currents is subject to the skin effect: most of the current flows near the outside of the wire. Assuming a sinusoidal current in a cylindrical straight wire of infinite length, the sectional current distribution is formulated using Bessel functions, which is determined by the wire's material properties, frequency, and diameter. The conductivity and permeability of the wire's material are relevant to the skin effect.
The skin effects are characterized by the skin depth for a one-dimensional half-space model, which decreases for higher frequency () and larger permeance () or conductivity (). You can select the wire material from four choices, in which iron the shows smallest because of its large permeability. The current distribution is shown in the graphics both by curves and by colors. The impedance per unit length is shown in the inset.
δ=
2/(ωμσ)
ω
μ
σ
δ
Reference
S. Takeyama, Theory of Electromagnetic Phenomena (in Japanese), Tokyo: Maruzen, 1944.