Defining Calculation Requests

Define the calculation requests in CADFEKO.

  1. Define far field data.
    1. Number of theta points: 37
    2. Number of phi points: 73
    3. File name: Browse for the .ffe file
    Tip: Click on Field data on the Construct tab to find all the field data types. Select Define far field data.
  2. Define spherical modes data.
    1. File name: Browse for the .sph file.
      Tip: Select Import spherical modes data from file.

Define near field data.

  1. Select Define near field data file structure.
    1. Source type: Load from .efe and .hfe file.
    2. E-field file: Browse for the .efe file.
    3. H-field file: Browse for the .hfe file.
    4. Coordinate system: Spherical
    5. Radius (R): 0.45
    6. Number of points along theta: 37
    7. Number of points along phi: 73
    8. On the Workplane tab set the following
      1. Origin: (helix_centre, helix_centre, helix_centre)
      2. U vector: (1, 0, 1).
      Tip: If changes are made to the number of field points in the full wave helix model, the same changes should be made in the field data definitions.
  2. Create a far field receiving antenna request.
    1. Field data: FarFieldData1
    2. On the Workplane tab set the following:
      • Origin: (helix_centre, helix_centre, helix_centre)
      • U vector: (1, 0, 1)
  3. Create a spherical modes receiving antenna request.
    1. Field data: SphericalModesData1
    2. Set the Workplane identical to that set in the far field receiving antenna request.
    3. On the Advanced tab select Use far field approximation.
      Tip: The spherical modes source requires that no geometry breaches the far field distance of the source. Feko will give a warning if this is the case.
  4. Create a near field receiving antenna request.
    1. On the General tab select Combine individual faces
    2. Field data: NearFieldData1
  5. Set the radiated power to 100W.
    Tip: To set the radiated power, either double-click on Power in the tree, or select from the Source/Load tab. Select the option Total source power (no mismatch).
    Note: The Yagi antenna was positioned and rotated to aim its first side-lobe at the helix.
    Note: A model of the full solution is provided. The ideal receiving antenna calculates the coupling assuming a matched load. The helix antenna is loaded with its complex conjugate impedance. The power in the load represents the total power received by the antenna. Results can then be compared directly.