# Creating a Planar Multilayer Substrate

Create a planar multilayer substrate by searching and navigating the documentation.

1. Search for ground in the integrated help.
The results returned in response to the ground query includes GroundPlane (object).
2. Double-click GroundPlane (object).
3. View the GroundPlane (object).
Note:

Since there can only be a single ground plane in a CADFEKO model, the GroundPlane (object) does not reside in a collection.

The absence of a Parent Collection List indicates that the ground plane can not be created using the :Add... method.

4. Navigate to the .DefinitionMethod property in the integrated help.
Note: The .DefinitionMethod property is set by the GroundPlaneDefinitionMethodEnum.
Note: You have the option to specify either Homogeneous, PEC, PMC, HalfspaceReflectionCoefficient, HalfspaceSommerfeld or MultiLayerSubstrate. For this example, we will use MultilayerSubstrate.
6. Change to MultilayerSubstrate using the following syntax:
my_project.GroundPlane.DefinitionMethod = cf.Enums.GroundPlaneDefinitionMethodEnum.MultilayerSubstrate
Note: This is similar to creating a planar multilayer substrate in CADFEKO GUI with default properties. One layer is created by default with the top and bottom layers consisting of free space and extending into infinity.
Attention: The first layer is indexed as one in the automation which differs from the CADFEKO graphical user interface.

We want to add a layer to the multilayer substrate. The layer will form part of a collection of layers for the GroundPlane (object).

my_project.GroundPlane.Layers:Add(2, "None", "0.351", myDiel2)
my_project.GroundPlane.Layers:Modify(3, "PEC", "0.2", my_diel)