[[Image:PMOM51(2).png|thumb|600px|Coupling gap sources in the Port Definition dialog by associating more than one source with a single port.]]
=== 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.Cube]]'s [[Planar Module]], you can use the following types of sources to define ports: