== Multiport Networks ==
[[File:twoport1.png|thumb|400px| Cascading two two-port network devices.]]
[[File:twoport2.png|thumb|400px| The property dialog of a multiport network device.]]
[[File:twoport3.png|thumb|400px| The property dialog of the Complex Impedance device.]]
A multiport network is a frequency-domain âblack-boxâ block that is modeled by its S-[[parameters]] as a function of frequency. [[RF.Spice]] currently offers the following models:
[[File:twoport1.png|thumb|400px| Cascading two two-port network devices.]]
[[File:twoport2.png|thumb|400px| The property dialog of a multiport network device.]]
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* Complex Impedance (a two-pin device)
* One-port (a two-pin device)
Besides entering the S-parameter values manually using in the parameter table, you can directly import these values from a text file with a ".TXT" file extension. For this purpose, click the button labeled "Load from File..." in the property dialog. This opens up the standard [[Windows]] Open dialog, with the file type set to text files. Browse your folders and select the text file to load the data from. The S-[[parameters]] you import to [[RF.Spice]] can come from manufacturer data sheets or they can be generated by electromagnetic simulation suites such as [[EM.Cube]]. For example, among [[EM.Cube]]'s computational modules, the FDTD, Planar MoM, Wire MoM and Surface MoM simulation engines all generate S-parameter text files for structures with port definitions. These files can directly be loaded into [[RF.Spice]].
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[[File:twoport3.png|thumb|400px| The property dialog of the Complex Impedance device.]]
===The Complex Impedance Device ===
Freq Real(z11) Imag(z11)
Note that the default reference impedance of the Complex Impedance is zero and must always stay zero to function properly. In order to have a fixed impedance element, define the same Real(z11) and Imag(z11) values for the minimum and maximum frequencies of your circuit. Due to the interpolation between these two values, you will always get the same impedance value at all the frequencies in between those two limits.
== Generic Transmission Lines ==