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Torben Voigt

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  1. lostarmour liked a post in a topic by Torben Voigt in ERROR 33238: Not enough memory available on the hard disk for an out-of-core file   
    Hi @lostarmour,
     
    Use the attached model: 08262019_Feko_two_blades_alt_2018.cfx
    What you probably didn't do is coarsening the mesh.
  2. bouvy liked a post in a topic by Torben Voigt in Batch Script Error   
    Hi @bouvy,
     
    Does running a simulation from CADFEKO work?
  3. MvdM liked a post in a topic by Torben Voigt in ERROR 116: The ratio of the segment radius to length is too large   
    Hi @SUG,
     
    FEKO assumes wires to be thin. This means that a segment (= mesh part of a wire) should not be shorter than 5 times the radius of the wire. Else using cylinders is recommended. Looking at your screenshot, you should clearly model the coil as a cylinder. The attached model shows the idea.

    coil.cfx
  4. Bidisha Barman liked a post in a topic by Torben Voigt in Element Gain Pattern   
    Hi @Bidisha Barman,
     
    Maybe you can make use of the "Scope" in the far field request. There you can select which faces/wires are taken into account for the far-field calculation. You could for example select only those faces from the one element you're interested in.
  5. Marcus Chang liked a post in a topic by Torben Voigt in something wrong in far field pattern result when using near field source   
    Hi @Marcus Chang,
     
    In the model where the near field is requested, the Start and End values of U are defined from positive to negative:

    Therefore when trying to use as near field source, you should rotate the workplane of the source (or of the field data) so that the orientation agrees with the original model.
  6. elaiyabharathi liked a post in a topic by Torben Voigt in design of meander line antenna for the frequency of 2.5Ghz   
    Hi @elaiyabharathi,
     
    The basics of Feko are easy to learn by having a look at the GettingStarted.pdf and the ExampleGuide.pdf (...\Altair\2018\help\feko\pdf). But of course feel free to attach a descrption of the geometry here and I will be happy to assist.
  7. BrianFEKO liked a post in a topic by Torben Voigt in Simple Microstrip with MoM   
    Hi @BrianFEKO,
     
    A region is created when faces form a fully closed volume. As soon as a region is present you can define the properties inside (e.g. set medium to some dielectric). The solver (MoM as default) will then use the Surface Equivalence Principle (SEP) to represent the region. I.e. the faces do behave as if there'a volume, without actually havin to mesh the volume. A surface mesh is sufficient. Note, one can also use Volume Equivalence Principle (VEP) instead of SEP. In that case the volume is discretized in tetrahedras. If not using MoM, with FEM geometry is also meshed with tetrahedras, with FDTD the whole problem is discretized with voxels (cuboids).
     
    In your model, the substrate is modelled with panar Greens functions instead of a volume. That's a very efficient method for printed structures, because the substrate won't require a mesh. 
     
    In my graph you se the real part of the input impedance of VoltageSource1.
     
    De-embedding unfortunately isn't supported directly in FEKO. It's under development but unclear when it will be available.
  8. BrianFEKO liked a post in a topic by Torben Voigt in Simple Microstrip with MoM   
    Hi @BrianFEKO,
     
    Any kind of port calibration would have to be done manually, e.g. with the help of lua scripting in POSTFEKO (e.g. adjusting S11 with some calibration model). Unfortunately I'm not an expert on this.
  9. RF Engineer liked a post in a topic by Torben Voigt in Sources used in CMA   
    Hi @dilaawaiz,
     
    I think UserManual.pdf chapter 2.22 Sources would be a good starting point.
  10. MOHAMED HAMDALLA liked a post in a topic by Torben Voigt in wire segment ports in EDIT FEKO   
    Hi MOHAMAD HAMDALLA,
     
    in CADFEKO you can activate Macro recording, which will then "record" the steps you do in CADFEKO and create a lua script from it. Very easy, even for unexperienced programmers.

  11. bouvy liked a post in a topic by Torben Voigt in Directivity Results Too Low   
    Hi bouvy,
     
    Sorry, it seems I forgot to attach the models. It's a reduced test model, antenna only. I asume the more faces break the > lambda/10 rule for the RCA ground, the less acurate the results get. Comparing to Sommerfeld ground, the test model is quite close.
    Model is attached.
    test_model_reduced_BO.cfx
  12. bouvy liked a post in a topic by Torben Voigt in Directivity Results Too Low   
    Hi bouvy,
     
    Coming back to your original assumption that the Directivity should be ~3 dB larger than for an isotropic radiator. Could you please clarify why you expect this? And please remember: Directivity will not be calculated when using infinite dielectric ground. Only Gain will be calculated.
     
    Apart from the results, FEKO 7 is quite outdated. If possible you should install the current version of FEKO (2018.1).
  13. bouvy liked a post in a topic by Torben Voigt in Directivity Results Too Low   
    Hi bouvy,
     
    The attached model gives a maximum Directivty of 2.49 dBi. Please note that for the Reflection Coefficient Approximation a minimum distance of lambda/10 should be between ground and segments/elements. That's why warnings are given:
     
    WARNING   667: A segment is close to the ground
    WARNING   668: A triangle is close to the ground
     
    I compared with Exact Sommerfel Integrals where the maximum Directivity is slightly higher (3.19 dBi). I assume that the lower the frequency, the worse the results, because the assumption of segments/elements being > lambda/10 away from the ground not fulfilled.
     
    Due to the small distance geometry and ground (1 cm) the Reflection Coefficient Approximation should only be used for frequencies > 30 GHz. I would recommend using Exact Sommerfeld Integrals instead.

     
    Please also note, that for dielectric halfspaces the loss in the dielectric is unknown and therefore only Gain will be computed (Directivity = Gain).
  14. hykr liked a post in a topic by Torben Voigt in Conformal Antenna Design   
    Hi hykr,
     
    One way would be using the "Project" function in CADFEKO (see attached video). However, the length of edges will change if they aren't orthongonal to the direction of curvature, It will depend on the degree of curvature, how much the length will change. For complex models there may be better solutions.
     
    Regarding the best solver, this of course depends strongly on complexity and size of yor model. In case there are both small/complex parts and large parts, it may be feasible to decompose the mode, e.g. by replacing small/complex parts by equvalent near fields.
     
    If you could attach an example model, I may be able to help more.
    video_how_to_project.mp4
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