=== Defining Independent & Coupled Ports ===
Ports are used in a planar structure to order and index the sources for calculation of circuit [[parameters]] such as scattering (S), impedance (Z) and admittance (Y) [[parameters]]. In EM.Picasso, you can use one or more of the following types of sources to define ports:
* Gap Sources
* De-Embedded Sources
Ports are defined in the '''Observables''' section of the navigation tree. You can define any number of ports equal to or less than the total number of sources in your project. If you have N sources in your planar structure, then N default ports are defined, with one port assigned to each source according to their order on the navigation tree. Note that your project can have mixed gap and probes sources as well as active lumped element sources on PEC and slot traces or vias. You can also couple ports together to define coupled [[Transmission Lines|transmission lines]] such as coupled strips (CPS) or coplanar waveguides (CPW).
[[Image:Info_icon.png|40px]] Click here to learn more about the '''[[Common_Excitation_Source_Types_in_EM.Cube#The_Port_Definition_Observable | Port Definition Observable]]'''.