Changes

=== Physical Line Calculations Calculators and Design Designers ===

When you place a generic T-line part in your circuit, you have to specify its characteristic impedance (Z0), effective permittivity (eeff) and attenuation constant (alpha). Or you may accept the default values Z0 = 50, eeff = 1, and alpha = 0. In the case of physical transmission line parts like mircostrip, coaxial line or CPW, you specify the physical [[parameters ]] of the line such as various dimensions and material properties. In that case, [[RF.Spice A/D]] then automatically calculates the necessary transmission line [[parameters ]] at the time of simulation based on your physical data at the time of simulation. Oftentimes, you may want to design a 50Ω transmission line of a certain type, or calculate and compare the characteristics of several transmission line types. 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_g = λ₀ / √ε_eff, where λ₀ = c/f is the free space wavelength at the operational frequency.

=== Physical For every physical transmission line type listed above, the '''Device Manager''' of [[RF.Spice A/D]] provides a corresponding '''Line Calculators ==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_c) and dielectric attenuation constant (α_d), both in Neper per meter (Np/m). Note that the total attenuation constant is the sum of these two: α =α_c + α_d.

The Device Editor {{Note| You can convert the values of [[RFattenuation constant from Np/m to dB/m using the relationship: 1Np = 8.Spice]] provides ten line calculators and ten designer tools for all the transmission line types listed 6859dB. }}  Another practical need in the above table. These tools are accessible form the RF Menu of the Device Editor. The design is to quarter-wavelength line calculators take the substrate properties and the physical dimensions of a line types and calculate its characteristic impedance (Z0) and effective permittivity (eeff)segments. The Line Calculator dialog also has an "Operational Frequency" input with a default frequency of 1GHzIn this case, which is used to you must 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 (as defined by &alphalambda;_cg) and dielectric attenuation constant (= &alphalambda;_d0), both in Neper per meter (Np/m). Note that the total attenuation constant is the sum of these two: &alpharadic; = &alphaepsilon;_ceff + , where &alphalambda;_d0. Also, you can convert these values from Np= c/m to dB/m using f is the relationship: 1Np = 8.6859dBfree space wavelength at the operational frequency.

=== Physical Line Designers === Oftentimes, you may want to design a 50Ω transmission line of a certain type, or calculate and compare the characteristics of several transmission line types. For every physical transmission line type, [[RF.Spice]] also provides a designer tool. The designer ignores conductor and dielectric losses and calculates the physical dimensions of the line for a given value of the characteristic impedance Z0. For example, given a substrate with thickness h and relative permittivity ε_r, the "Microstrip Designer" calculates the microstrip width in mm for a given value of Z0 (50 Ohms by default). Some line type like CPW and coaxial line have more than one dimensional parameter that can be varied. For example, CPW has slot width (w) and center strip width (s), while coaxial line has inner and outer conductor radii. In such cases, the Line Designer dialog provides radio button options to fix one parameter and vary the other.