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Coaxial Cable Impedance Calculator

Turn cable geometry and dielectric into impedance, electrical length and signal delay.

conductor's outside diameter
shield's inside diameter; D must exceed d
applies to both diameters
air ≈ 1; solid polyethylene ≈ 2.25
used for total C, L and one-way delay
impedance does not depend on length

Lossless, non-magnetic coax: Z₀ = ln(D/d)/(2π√εr) · √(μ₀/ε₀). This ignores conductor loss, skin effect, braiding, dielectric dispersion and connectors; use the cable datasheet for a manufactured part.