Impedance, capacitance and inductance of coaxial cable is calculated by the following formulas:
Formula 1
Where:
Z is the impedance in ohm (Ω)
ε is the dielectric Constant (vacuum = 1)
D is the external diameter in centimeters (cm)
d is the internal diameter in centimeters (cm)
Note: Any unit can be used to Express the diameters (internal and external), as the ratio between them is na absolute value.
Formula 2
Where:
C is the capacitance in picofarads (PF)
ε is the dieletric constant
L is the length in centimeters (cm)
D is the external diameter in centimeters (cm)
d is the internal diameter in centimeters (cm)
Formula 3
Where:
Lx is the inductance in microhenry (uH)
µ is the relative permeability (for non magnetic materials is 1)
L is the length in centimeters (cm)
D is the external diameter in centimeters (cm)
d is the internal diameter in centimeters (cm)