# 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 centimetres.
2. Define the following variables:
• freq = 1.645e9 (The operating frequency.)
• lambda = c0/freq * 100 (The wavelength in free space.)
• wa = 12.96 (The width of the waveguide.)
• wb = 6.48 (The height of the waveguide.)
• ha = 55 (The width of the horn.)
• hb = 42.8 (The height of the horn.)
• wl = 30.2 (The length of the waveguide section.)
• fl = wl - lambda/4 (The position of the feed wire in the waveguide.)
• hl = 46 (The length of the horn section.)
• pinlen = lambda / 4.56 (The length of the pin.)
3. Define a dielectric medium, air.
• Relative permittivity: 1
• Dielectric loss tangent: 0
• Label: air
4. Create the waveguide section.
1. Create a cuboid.
• Definition method: Base corner, width, depth, height
• Base corner (C): (-wa/2, -wb/2, -wl)
• Width (W): wa
• Depth (D): wb
• Height (H): wl
5. Set the region of the cuboid to air.
6. Select the four faces that represent the waveguide boundary walls and set to PEC. Select all faces of the waveguide section, except the following faces:
• The face at the origin.
• The face where the FEM modal port will be located (opposite the face at the origin.)
7. Set the solution method for the air region to FEM.
Tip: Open the Region properties dialog and click the Solution tab. From the Solution method list, select Finite Element Method (FEM).
8. Create the horn section.
1. Create a flare.
• Definition method: Base centre, width, depth, height, top width, top depth
• Bottom width (Wb): wa
• Bottom depth (Db): wb
• Height (H): hl
• Top width (Wt): ha
• Top depth (Dt): hb
9. Delete the face at the origin.
10. Delete the face opposite to the face deleted in Step 9.
11. Union all parts.
12. Add a FEM modal port to the back face of the waveguide.
13. Add a FEM modal source to the port. Use the default settings.
14. Set the total source power (no mismatch) to 5W.
15. Set the frequency to freq.
16. Specify the symmetry about 2 principal planes:
• X=0: Magnetic symmetry.
• Y=0: Electric symmetry.
Tip: Exploit model symmetries (if it exists) in a large or complex model to reduce computational costs.