# Example: Cable Reference Direction - Connected to an Installation

Consider an example where a cable path is defined within a distance of $\frac{\lambda }{5}$ from a ground plane.

The cable cross section orientation is indicated by:
• dotted green line: $v$ vector
• blue line: $u$ vector
• solid dark green line: cable reference direction
Note: CADFEKO tries to orientate the $v$ vector at the start of the cable path to align with the cable reference direction automatically using the constraint that the $u$ and $v$ vector must be perpendicular to the cable path.

The cable reference direction is defined normal to the installation or ground (in the “up” direction) and is not pointing towards it. In the cable schematic the cable is connected to the installation and acts as a return path for the signal. No twist angle is defined along the cable path.

Note: This option can be used with only one signal in the cable harness as the installation acts as the return path.