# Creating the Model

Create the model in CADFEKO. Define any ports and sources required for the model. Specify the operating frequency or frequency range for the model.

1. Set the model unit to millimeters.
2. Define the following variables:
• epsr = 9.5 (The relative permittivity of the substrate.)
• r = 0.63 (The radius of the feed element.)
• hBig = 1 (The height of the feed base.)
• rBig = 2.25 (The radius of the feed base.)
• rDisk = 60 (The radius of the ground.)
• rDome = 12.5 (The radius of the inner dome.)
• rDomeBig = rDome + 5.5 (The radius of the outer dome.)
• h = 7 (The height of the feed element.)
• fmin = 3e9 (The minimum frequency.)
• fmax = 6e9 (The maximum frequency.)
• lambda = c0/fmax * 1000 (The wavelength in free space. [mm])
3. Define a named point:
• excite_b: (0, 6.5, -1)
4. Define a dielectric medium, air.
• Relative permittivity: 1
• Dielectric loss tangent: 0
• Label: air
5. Define a dielectric medium, dome.
• Relative permittivity: epsr
• Dielectric loss tangent: 0
• Label: dome
6. Define a dielectric medium, isolator.
• Relative permittivity: 2.33
• Dielectric loss tangent: 0
• Label: isolator
7. Create a new workplane.
• Origin: excite_b
• Set the new workplane as the default workplane.
8. Create the outer conductor for the feed pin.
1. Create a cylinder.
• Radius (R): rBig
• Height (H): hBig
• Label: FeedBase
9. Create the inner conductor for the feed pin.
1. Create a cylinder.
• Radius (R): r
• Height (H): hBig + h
• Label: FeedPin
10. Set the region that makes up the feed base to isolator.
11. Set the default workplane to Global XY.
12. Create the finite ground plane.
1. Create an ellipse.
• Radius (U): rDisk.
• Radius (V): rDisk.
13. Create the inner dome.
1. Create a sphere.
• Label: InnerDome.
14. Create the outer dome.
1. Create a sphere.
• Label: OuterDome.
15. Union all parts and rename the Union to DRA.
16. Delete the bottom faces of each dome.
17. Set the region of the inner dome to dome.
18. Set the region of the outer dome to air.
19. Reset any suspect regions to their correct media.
Tip: Suspect regions are overlapping regions joined in a union.
20. Set the solution method for all regions to FEM.
Tip: Open the Modify Region dialog and click the Solution tab. From the Solution Method drop-down list, select Finite Element Method (FEM).
21. Set all faces in the model to PEC.
22. Set the following faces to the Default face medium.
• The top and bottom faces of FeedBase.
• The remaining dome faces.
23. Add a FEM modal port to the bottom face of FeedBase.
24. Add a FEM modal source to the FEM modal port.
25. Set a continuous frequency range from fmin to fmax.