Shared Reference Planes

When ports have shared reference planes:

•  The length of each reference plane is the same.
•  Calibration standards are composed of multiple coupled lines as shown below.
•  Coupling between the fringing fields of the ports is removed to provide a more accurate result.
•  Coupling between feedlines is removed over the entire length of the reference plane.
•  Sonnet does not calculate a Z0 or Eeff. This is because the lines are treated as coupled, and Z0 and Eeff are only valid for a single transmission line. Two coupled lines, for example, have two modes, and thus two  Z0 and Eeff values. If you try to plot the  Z0 or Eeff value of a shared port, you will receive an error message. If you are looking at the text output results, you will see “mp” de-embedding codes in place of the  Z0 and Eeff values.

The only ports which can have shared reference planes are orthogonal box-wall ports and orthogonal co-calibrated ports with a Sonnet box ground node connection. For orthogonal boxwall ports, only ports on the same box wall may be shared. Orthogonal box-wall ports share reference planes by default. A user may choose to make these reference planes independent. See Independent Reference Planes for details on changing the reference planes from shared to independent.