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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

Range

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