How is a port modeled in Sonnet?

Geometry Elements - Ports

A port in Sonnet is modeled as a two-terminal device whose normalizing impedance is represented by four numbers. First is the real part in ohms. Next comes the reactive part in ohms. Third is the inductive part in nanohenries (nH). The last number is the capacitive part in picofarads (pF). The inductive and capacitive part modify only the reactive portion of the load, they are included so you do not have to manually re-calculate the reactive part at each frequency.

The resistance, reactance and inductance are all connected in series when the specific normalizing impedance is calculated at each frequency of analysis as illustrated below. The capacitance is connected in parallel with the result and then the final normalizing impedance at the frequency of analysis is calculated.

Ports, of any type, are not allowed on diagonal lines and are not allowed to overlap each other (just touching is permitted). The analysis engine tests for these error conditions.

In em, the default normalizing impedance is 50 ohms. If you would like a different normalization, refer to How do I change the normalizing impedance for a port?

For a detailed discussion of ports and how they are used in Sonnet, please see the Ports chapter in the Sonnet User's Guide.