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Agilent Technologies

Coaxial Cable Types (RG6, RG8, RG58, RG59, RG214)

This symbol is available in the schematic editor on the Coax Toolbar.

Model Parameters

Parameter Description Units Default Value
L Length mm null
Z0 Characteristic Impedance Ohm null
Er Dielectric Constant none null
kdb1 attenuation/meter, per sqrt(Mhz) none null
kdb2 attenuation/meter, per MHz none null


Single part models are available for six widely used cable types: RG-6, 8, 9, 58, 59, 214. These have a characteristic impedance of 50 ohms, except for RG-6 and RG-59 which are 75 ohms. In the Examples is a workspace, Coaxial_Cable.wsp, which presents a method for computing the required parameters from manufacturers data. It assumes that the characteristic impedance is readily available. The dielectric constant of the material between the inner and outer conductors is commonly given. This can also be computed if the "velocity factor (Vp)" or "velocity of propagation" is given. The dielectric constant (Er) equals:

Er = ( 1 / Vp 2 ).

The attenuation parameters are may be available. If not, they can be calculated from the curves of attenuation per 100 meters as a function of frequency. The example workspace facilitates the curve fit.

For the six parts included, the default parameters are listed in the following table.

  RG6 RG8 RG9 RG58 RG59 RG214
Zo 75.0 52.0 51.0 53.5 75.0 50.0
Er 1.78 2.26 2.26 2.26 1.45 2.26
Kdb1 .006734 .005264 .006229 .0138 .0085535 .00426
Kdb2 0 .69e-4 .70e-4 .1254e-3 0 0.1348e-3

Touchstone Translation None

Default SPICE Translation None