# 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 = 900e6 (The operating frequency.)
• f_min = 100e6 (The minimum frequency.)
• f_max = 1e9 (The maximum frequency.)
• d = 0.1 (Distance between the dipole and muscle sphere.)
• rA = 0.03 (Radius of the outer sphere.)
• rM = 0.025 (Radius of the inner sphere.)
• lambda = c0/freq (The wavelength in free space.)
2. Add the medium, Muscle_Parallel_Fibers_Ovine from the media library to the model.
3. Create a dielectric medium.
• Dielectric loss tangent: 0
• Relative permittivity: 1
• Label: air
4. Create the inner sphere.
• Centre: (0, 0, 0)
• Label: Muscle
5. Create the outer sphere.
• Centre: (0, 0, 0)
• Label: Air
6. Union the spheres, Muscle and Air.
7. Set the region of the inner sphere to Muscle_Parallel_Fibers_Ovine.
8. Set the region between the inner and outer sphere to air.
9. Set the solution method for the regions to FEM.
10. Create the dipole.
1. Create a line.
• Start point: (0, -lambda/4, -d)
• End point: (0, lambda/4, -d)
11. Add a wire port (vertex) to the middle of the line.
12. Add a voltage source to the port. (1 V, 0°, 50 Ω).
13. Set the total source power (no mismatch) to 1 W.
14. Set a continuous frequency range from f_min to f_max.
15. Specify the symmetry about 2 principal planes:
1. X=0 plane: Magnetic symmetry.
2. Y=0 plane: Electric symmetry.
Tip: Exploit model symmetries (if it exists) in a large or complex model to reduce computational costs.