Coaxial Cable Equations

Flexible braided coax coaxial cable drawing

Most often used braided flexible (shown at left) and solid tube semi-rigid (shown at right) types are listed here.

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Capacitance (C) = Inductance (L) = Impedance (Z₀) = Velocity = %c (speed of light in a vacuum) Cutoff Frequency = (here is a calculator) Reflection Coefficient = VSWR = Peak Voltage =	, where
		d =	outside diameter of inner conductor in inches
		D =	inside diameter of outer conductor in inches
		S =	maximum voltage gradient of cable insulation in volts/mil
		ε (ε_r) =	relative dielectric constant
		K =	safety factor
		f =	frequency in MHz

Cable attenuation is the sum of the conductor losses and the dielectric losses per the following equations. ρ_r = 1 for copper, 10 for steel	, where	d =	outside diameter of inner conductor in mm
		D =	inside diameter of outer conductor in mm
		ε_r =	relative dielectric constant
		f =	frequency in GHz
		ρ_rd =	inner conductor material resistivity relative to copper
		ρ_rD =	outer conductor material resistivity relative to copper
		δ =	skin depth

Webmaster: Kirt Blattenberger, BSEE, UVM 1989