simple electric characteristics computation
select coaxial cable or twin-lead.

(inner)conductor diameter
For coaxial cable input diameter of inner conductor, for twin-lead input diameter of conductor in mm unit.

outer diameter / conductor spacing
For coaxial cable input inner diameter of outer conductor, for twin-lead input conductor spacing in mm unit.

select dielectric material from PE (poly-ethylene), CPE (formed poly-ethylene), PTFE (Tefron), PVC (poly-vinyl-croride), AIR (air).

(select construction and dielectric material, then input size and press "submit" to computing some electrical characteristics.)

Frequentry used electrical characteristics of wire and cable is as follows. The resistance, capacitance, inductance and conductance are called primary parameters, and used for low frequency applications. The characteristic impedance, velocity ratio (phase constant) and attenuation are called secondary parameters and used for high frequency applications.


The resistance of cable varies largely with frequency because of skin effect and proximity effect of conductor. (use "wire-gauge calculation" for DC-resistance.)


The capacitance of cable depends on geometrical structure and dielectric constant of insulation material. The dielectric constant varies with frequency and temperature, but for poly-ethylene and poly-popylene and tetra-furuolo-ethylene, it is almost independent of frequency and temperature. The dielectric constant of PVC varies largely with temperature, frequency and construction of compound.


The inductance of cable depends on geometrical structure and permiability of conductor and insulation material. But its value for cable is very small as other electrical parts, it is neglectable for most of cases.


The conductance of cable depends on insulation registance at DC, buf it depends on dielectrical loss at high freqency.

characteristic impedance

The characteristic impedance varies largely with frequency at low frequency range. But it is almost constant at high frequency range about few MHz and higher.

velocity ratio

The velocity ratio of cable depends on dielectric constant of insulation material.


The attenuation constant of cable depends on conductor resistance and dielectric loss of insulation. At lower frequency range as lower than about 1 GHz, dielectric loss is negligible.
These characteristics is analytically computable at only very simple constructions. We must usr numerical method for complex structue. But values for these basic constructions are usefull for proximation at many cases.