# 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. Define the following variables:
• freq = 400e6 (The operating frequency.)
• lambda = c0/freq (The wavelength in free space.)
• lr = 0.477*lambda (Length of the reflector.)
• li = 0.451*lambda (Length of the active element.)
• ld = 0.442*lambda (Length of the directors.)
• d = 0.25*lambda (Spacing between elements.)
• h = 3 (Height of the antenna above ground.)
• epsr = 10 (Relative permittivity of the ground.)
• sigma = 1e-3 (Conductivity of the ground.)
• wireRadius = 1e-3 (Radius of the wire.)
2. Create the dipole (driven element) of the Yagi-Uda antenna.
1. Create a line.
• Start point: (0, - li/2, h)
• End point: (0, li/2, h)
• Label: activeElement
2. Add a wire port (vertex) to the middle of the line.
3. Add a voltage source to the port. (1 V, 0°, 50 Ω).
3. Create the reflector of the Yagi-Uda antenna.
1. Create a line.
• Start point: (-d, -lr/2, h)
• End point: (-d, lr/2, h)
• Label: reflector
4. Create the three directors of the Yagi-Uda antenna.
1. Create three lines.
Line Start point End point Label
1 (d, -ld/2, h) (d, ld/2, h) director1
2 (2*d, -ld/2, h) (2*d, ld/2, h) director2
3 (3*d, -ld/2, h) (3*d, ld/2, h) director3
5. Create a new dielectric called ground with relative permittivity set to epsr and conductivity to sigma.
6. Set the lower half space to ground using the exact Sommerfeld integrals.
7. Set the frequency to freq.
8. Specify the symmetry about the Y=0 plane as Electric symmetry.
Tip: Exploit model symmetries (if it exists) in a large or complex model to reduce computational costs.