Skin Depth Calculator — RF Conductor Loss | RFCalcLab
Calculate skin depth for high-frequency conductors to determine AC resistance and conductor losses. Analyze the skin effect in copper, silver, and gold for microwave and RF circuit design.
How to Use the Skin Depth Calculator
Select a conductor material or enter custom resistivity (ρ) and relative permeability (μr). Input the frequency to see how deeply the RF current penetrates the metal surface. The tool evaluates δ = √(ρ / (π·f·μr·μ₀)), where μ₀ = 4π×10⁻⁷ H/m; skin depth is the depth at which current density falls to about 37% (1/e) of its surface value.
At high frequencies, current crowds near the surface (the skin effect), increasing the effective AC resistance. For copper (ρ ≈ 1.72×10⁻⁸ Ω·m, μr = 1) the skin depth is about 66 µm at 1 MHz but shrinks to only ~2.1 µm at 1 GHz — note that it scales with 1/√f, so a 100× rise in frequency reduces depth by 10×. This is why many RF components are silver or gold plated, since the current never reaches the cheaper base metal underneath.
The results help in selecting appropriate plating thicknesses and designing high-Q inductors or low-loss transmission lines. A practical rule is to make conductive plating at least three to five skin depths thick so the surface metal carries essentially all the current. Magnetic conductors such as nickel or iron have high μr, giving far smaller skin depths and much higher loss at RF — one reason ferrous connectors and PCB finishes are avoided on critical signal paths.
Related Topics
- skin depth calculator
- skin effect
- conductor loss
- RF conductor
- copper skin depth
- eddy current
Frequently Asked Questions
- What is Skin Effect?
- Skin effect is the tendency of an alternating electric current (AC) to become distributed within a conductor such that the current density is largest near the surface, and decreases with greater depths in the conductor.
- Why is skin depth important at RF?
- At RF frequencies, skin depth is extremely small (micrometers). This means only the surface layer of a conductor carries current. Plating a cheaper metal with a highly conductive one (like silver) significantly reduces loss.
- Does material permeability affect skin depth?
- Yes. Magnetic materials (high permeability) like iron or nickel have much smaller skin depths than non-magnetic materials like copper, leading to higher losses at high frequencies.