Creating a Double Layered Cable Shield

A double cable shield consists of two shield layers. CADFEKO supports any combination of the shield types, solid, braided and frequency-dependent for the inner and outer layer of the shield.

When creating a double cable shield, you need to specify the shield layer impedance and admittance for the inner layer and outer layer of the shield. A gap size also needs to be specified between the inner and outer layer of the double shield.


Figure 1. Illustration of double cable shield.
Note:

The total shield radius is the outer radius of the shield. The radius is used as a common reference point between the inner and outer layer when stretching the shield.

The stretching range is applicable when a braided (Kley, Vance, Tyni and Demoulin) layer definition is used on the inner layer or outer layer.

  1. On the Cables tab, in the Definitions group, click the  Cable shield icon.
  2. Under Shield layer(s), click Double to create a double layered shield.


    Figure 2. The Create cable shield dialog.
  3. Under Shield layer(s), in the Gap between layers field, enter a value for the gap between layers. The gap should be greater than 0.
  4. On the Inner layer tab, create a solid, braided or frequency dependent shield layer.
  5. On the Outer layer tab, create a solid, braided or frequency dependent shield layer.
  6. On the Advanced tab, under Stretching of the shield, for the Optimisation method drop-down list, select Maximise optical coverage, to automatically calculate the optimal weave angle and optical coverage for maximum shielding for the braided inner or braided outer layer.

    The minimum and maximum radius of the double shield is indicated by the top and bottom entry in the Total shield radius column.



    Figure 3. The Create shield dialog, setting the optimisation method for the stretching of a braided shield layer.
    Note: For a double braided shield, the stretching of the shield is limited to the stretching capability of both braided layers. The stretching range (Total shield radius range) could be smaller for a double braided shield than for a single braided shield, depending on the braid parameters selected for each shield.
  7. On the Advanced tab, under Stretching of the shield, from the Optimisation method drop-down list, select Specify manually to manually define values in the stretching table:
    • In the Total shield radius field, edit an existing radius.
    • In the Inner layer or Outer layer Weave angle column, enter a value for the weave angle in degrees.


    Figure 4. The Create shield dialog, setting the optimisation method for the stretching of a braided shield layer.
    Note:
    • Total shield radius must be between the minimum radius (first row, first cell) and maximum radius (last row, first cell).
    • The values in the Inner layer Optical coverage and Outer layer Optical coverage columns, are calculated automatically from the Total shield radius, Inner layer Weave angle and Outer layer Weave angle.
    • The Inner layer Weave angle or Outer layer Weave angle values must be between the minimum angle (first row, third cell) and maximum angle (last row, fifth cell).
  8. In the Label field, add a unique label for the double cable shield.
  9. Click Create to create the double cable shield and close the dialog.