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 millimetres.
  2. Define the following variables:
    • freq = 2.4e9 (The operating frequency.)
    • lam0 = c0/freq*1000 (The wavelength in free space.)
    • epsr = 2.08 (Relative permittivity of the substrate.)
    • patchLength = 41 (The length of the patch antenna.)
    • patchWidth = 35 (The width of the patch antenna.)
    • h = 3.5 (The height of the substrate.)
    • pinOffset = -11 (Distance between the feed pin and patch centre.)
    • wireRadius = 0.1 (The radius of the feed pin wire.)
  3. Create the patch. The patch is the base element to be used in the finite antenna array.
    1. Create a rectangle.
      • Definition method: Base centre, width, depth
      • Base centre: (0, 0, 0)
      • Width (W): patchWidth
      • Depth (D): patchLength
  4. Create the feed line.
    1. Create a line.
      • Start point: (0, pinOffset, -h)
      • End point: (0, pinOffset, 0)
  5. Union all parts in the tree.
  6. Create a dielectric medium.
    1. Dielectric loss tangent: 0
    2. Relative permittivity: epsr
    3. Label: substrate
  7. Add a planar multilayer substrate (infinite plane) with a conducting layer at the bottom.
    1. Select Plane / ground.
      • Select Planar multilayer substrate from the Definition method drop-down list.
      • Thickness (Layer 1): h
      • Medium (Layer 1): substrate
      • Ground plane (Layer 1): PEC
      • Z value at the top of layer 1: 0
  8. Add a wire port (segment) to the middle of the line.
  9. Add a voltage source to the port. (1 V, 0°, 50 Ω).
  10. Set the frequency to freq.
    Note: The steps up to this point represents the base element. The next steps will create an array from the base element.
    Figure 1. Layout of the final array.

  11. Create a planar array.
    • Number of elements = 4 (in both the U and V dimensions)
    • Offset along X axis = lam0.
    • Offset along Y axis = lam0.
Convert an array into a custom array to allow an element to be rotated or repositioned with respect to one another. Rotate an element by modifying its local workplane. An element can also be deleted from the array.
  1. Convert the array into a custom array.
    Tip: For this example, the elements are not rotated, but you are encouraged to rotate a few of the elements after obtaining the initial results to investigate the effect on the array pattern.
  2. Delete the elements from the third row and third column. Only nine elements should remain.
  3. Solve the antenna array with the DGFM.
    Tip: Open the Solver Settings dialog, click the Domain Decomposition tab and then select the Solve model with Domain Green's Function Method (DGFM) check box.