Working with a Draftsman Transmission Line Table in Altium NEXUS

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Parent page: Working with Tables

The calculations applied in controlled impedance routing result in trace structures that aim to satisfy a target transmission line impedance, and therefore the board design’s high-speed and/or EMF requirements. The table's visual style is configurable in the Properties panel.

Board layers and their specified or calculated properties are accessed through the Layer Stack Manager, where impedance controlled routing layers are associated with definable Impedance Profiles. The board materials and dimensions in each profile are applied to its Transmission Line impedance calculations, which results in a given trace structure. The structure accommodates both single traces and differential pairs, and Stripline (internal) or Microstrip (surface) board layer formats.

See the Defining the Layer Stack for more information.

Since the structure and associated data for each Transmission Line definition in the board Layer Stack is important information for the PCB manufacturing process, Draftsman includes a dedicated Transmission Line Table object to document this information.

A placed Transmission Line Table with a range of cell formatting.
A placed Transmission Line Table with a range of cell formatting.

The table is populated by data drawn from the Layer Stack Manager and its Transmission Line impedance calculations.

The Transmission Line Table object is available for placement from the Place » Transmission Line Table command on the main menu, or from the Table objects drop-down menu on the Active Bar. After launching the Transmission Line Table placement command a new table object, populated with Layer and Impedance data is drawn from the board Layer Stack, is attached to the cursor. Move the cursor to the desired position then click to confirm the placement.

To retrieve the current/latest data from the Layer Stack use the Tools » Update Board command.

The position of a placed Transmission Line Table may be graphically changed by selecting within the table object and then dragging it to a new location. Note that the table cannot be graphically resized, but will automatically scale to accommodate the font and column properties specified in the Properties panel. Use the Properties panel to set the table style (colors, lines, font, etc.), and under its Columns tab, which data columns are displayed.