Electronics World Cover,TOC,and list of posted Popular Electronics articles QST Radio & TV News Radio-Craft Radio-Electronics Short Wave Craft Wireless World About RF Cafe RF Cafe Homepage RF Cafe in Morse Code Google Search of RF Cafe website Sitemap Electronics Equations Mathematics Equations Equations physics Manufacturers & distributors Engineer Jobs Twitter LinkedIn Crosswords Engineering Humor Kirt's Cogitations Engineering Event Calendar RF Engineering Quizzes AN/MPN-14 Radar 5CCG Notable Quotes App Notes Calculators Education Magazines Software,T-Shirts,Coffee Mugs Articles - submitted by RF Cafe visitors Simulators Technical Writings RF Cafe Archives Test Notes RF Cascade Workbook RF Stencils for Visio Shapes for Word Thank you for visiting RF Cafe!

Skin Depth (aka Skin Effect)
as a Function of Frequency, Permeability, & Conductivity

Skin Depth Equation Formula (aka Skin Effect)

Skin Depth of microstrip - RF CafeAs frequencies increase, conduction begins to move from an equal distribution through the conductor cross section toward existence almost exclusively near the surface. Depending on the conductor bulk resistivity (δs), at sufficiently high frequency all the RF current is flowing within a very small thickness at the surface. Furthermore, the current concentrates nearest to the surface that abuts the highest relative dielectric constant. Lower bulk resistivities result in shallower skin depths.

Skin Depth of round wire - RF CafeIn the case of a microstrip layout (to the right), the current concentrates nearest to the substrate dielectric material, although current does also concentrate at the other surfaces as well (redder regions). For a solid wire (to the left), the current concentrates on the outer surface. For this reason, when skin depth is shallow, the solid conductor can be replaced with a hollow tube with no perceivable loss of performance. Choice of a plating material can degrade performance (increase attenuation) if its bulk resistivity is greater than that of the copper.

Most common conductors have a relative permeability of very near 1, so for copper, aluminum, etc., a µ value of 4π* 10-7 H/m can safely be assumed. Magnetic materials like iron, cobalt, nickel, mumetals, and permalloy can have relative permeabilities of hundreds or thousands.

The equation for calculating the skin depth is given here:
          (click here table of calculated values)
          (click here for a skin depth calculator)

Skin depth equation formula

µ = permeability (4π* 10-7 H/m),  note: H = henries = Ω*s

π = pi

δs = skin depth (m)

ρ = resistivity (Ω*m)

ω = radian frequency = 2π*f (Hz)

σ = conductivity (mho/m),  note: mho [Electrical 'mho' symbol - RF Cafe] = Siemen [S]

Example: Copper @ 10 GHz (ρCu=1.69*10-8 Ωm)

Formula copper skin depth - RF Cafe

Try Using SEARCH to Find What You Need.  >10,000 Pages Indexed on RF Cafe !

Copyright 1996 - 2016
Webmaster:  Kirt Blattenberger, BSEE - KB3UON
Family Websites:  Airplanes and Rockets | Equine Kingdom

All trademarks, copyrights, patents, and other rights of ownership to images
and text used on the RF Cafe website are hereby acknowledged.