For every physical transmission line type listed above, the '''Device Manager''' of [[RF.Spice A/D]] provides a corresponding '''Line Calculator'''. The line calculators are accessible form the '''Tools Menu''' of the Device Manager. The line calculators take the substrate properties and the physical dimensions of a line types and calculate its characteristic impedance (Z0) and effective permittivity (eeff). The Line Calculator dialog also has an "Operational Frequency" input with a default frequency of 1GHz, which is used to calculate the guide wavelength of the transmission line at that frequency. Some of the line types, microstrip, stripline, coaxial line, twin-lead line and twisted-pair line, have loss [[parameters]]: dielectric loss tangent and metal conductivity. For these lines, the line calculator calculates the conductor attenuation constant (α<sub>c</sub>) and dielectric attenuation constant (α<sub>d</sub>), both in Neper per meter (Np/m). Note that the total attenuation constant is the sum of these two: α = α<sub>c</sub> + α<sub>d</sub>.
{{Note|You can convert the values of attenuation constant from Npm Np/m to dBm dB/m using the relationship: 1Np = 8.6859dB.}} {{Note|[[EM.Tempo]] is You can convert the values of attenuation constant from Np/m to dB/m using the relationship: 1Np = 8.6859dB.}}
Another practical need in RF design is to quarter-wavelength line segments. In this case, you must calculate the guide wavelength of the transmission line as defined by λ<sub>g</sub> = λ<sub>0</sub> / √ε<sub>eff</sub>, where λ<sub>0</sub> = c/f is the free space wavelength at the operational frequency.