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  1. MOHAMED HAMDALLA liked a post in a topic by mel in Coupling to wire at different orientations   
    Hi Mohamed
    You should be using the numerical green's function (NGF). Have a look at the "H.4 Optimise Waveguide Pin Feed Location" model in the Examples Guide.
  2. MOHAMED HAMDALLA liked a post in a topic by mvogel in Composite Materials In FEKO   
    I think the values are practical values, but I don't have a reference. I picked up the values from somebody else's example (presented publicly) and I have used it a few times myself in public examples. It would be wise for you to do an on-line search or literature search for typical values, but if the application is not critical, then these are good values to start with.
  3. MOHAMED HAMDALLA liked a post in a topic by JIF in wire segment ports in EDIT FEKO   
    The manual has an entire chapter on EDITFEKO and the PREFEKO language. The Appendix also describes each "card" in detail. I think all the documentation that you need is already available.
    Using EDITFEKO, this will entail breaking up the creating of the wire into three sections (thus, three BL cards). Two of the sections are for the sides and one is for the section in the middle. Ensure that the section in the middle is only one segment long and label it with the LA card. This allows you to then add a source or a load on the segment with that label. For a voltage source, you will then use the A1 source (segment port). If you want to add a vertex source, then only split your wire into two sections and label one of them (at least). Then add the A2 source (with the correct settings) on that label.
    Take @Torben Voigt's advice and start working with CADFEKO scripting (using Lua). It is much easier than EDITFEKO and you can use macro recording to see how to do some parts (also makes script creation much faster). But be sure to work through the intro section for scripting and the example in the Example guide.
  4. MOHAMED HAMDALLA liked a post in a topic by Torben Voigt in wire segment ports in EDIT FEKO   
    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.

  5. MOHAMED HAMDALLA liked a post in a topic by JIF in wire segment ports in EDIT FEKO   
    The error is correct. You are creating wires from the points that you read from the text files, but all the wires (built with BL card) have the default label (nl. 0). Later in the script you add three loads and an excitation, but you add it to labels such as "Line6.Wire6.Port2" and they don't exist (all your wire segments are labeled 0). You need label the wires with the LA card and then place the loads and the excitation on the correct label.
    Everything that you are doing can also be done in CADFEKO (with scripting), but I assume that you have a good reason to use EDITFEKO instead.
  6. SIakovlev liked a post in a topic by MOHAMED HAMDALLA in Multi plane waves simulation   
    First, thanks a lot for your continuous great help. I need to excite my structure by two plane waves simultaneously each of different frequency . is there any way to do this? hint: I don't want to use superposition theory. 
  7. MOHAMED HAMDALLA liked a post in a topic by Wilco Strydom in Modal excitation coefficient for multiple incident angles   
    Currently a CMA configuration with modal excitation coefficients where the source is a plane wave loop over multiple angles of incidence will only consider the final angle of incidence.
  8. MOHAMED HAMDALLA liked a post in a topic by Wilco Strydom in Control modes sorting in CMA   
    What is happening here is that the modes are assigned numbers so that we can consistently refer to a single mode across frequencies.
    At every frequency the *.out file will list the modes of that frequency in order of Modal Significance. The mode tracking algorithm will however determine mode numbering. In your example of getting modes in order 3-2-1, that simply means that at this frequency mode 3 is the most significant followed by mode 2 then lastly mode 1.
    When you request 6 modes you will only receive results for 6 modes at every frequency, but you will receive the most significant 6 modes at that frequency. This means that over the requested frequency range some modes will fall out of significance and new modes will enter significance. It is then very possible for a mode with the number 'mode 100' to be in the top 6 most significant modes at a later frequency.
    If you would like the modes numbered 1 to 6 at every frequency you can disable tracking in the *.pre file. The easiest way is to use EDITFEKO. The CMA request will look something like this:
    ** Characteristic modes OM: 6 : 1 : -1 ** CharacteristicModes1 With the last number indicating that tracking is disabled.
  9. MOHAMED HAMDALLA liked a post in a topic by Peter Futter in modal analysis of HMSIW slot antenna   
    Hi @banana22
    sorry for the delay getting back to you.
    the only difference between my simulation model and yours was that I increased the number of frequency point to 301 points in the band, 50 MHz steps. Then I only requested 10 modes - whenever FEKO reaches a discontinuity in the mode tracking, additional modes will be tracked. That is why I am able to plot modes numbers up to mode number 57 even though I only requested 10 modes. 
  10. MOHAMED HAMDALLA liked a post in a topic by andries in loading metallic materials   
    At higher frequencies, the skin depth of a metallic region quickly limits how deeply electromagnetic waves can penetrate a 3D object.  In FEKO, then, the method to model a metal is to:
    set the inside region to "free space"; and to set the face properties to a metal with a given thickness See evo2_modified.cfx for an example.  Note that I've also change your frequency settings to a single 1GHz frequency point.  You can, of course, change it back to a frequency range but I wouldn't expect the results to make sense all the way down to 1Hz.  The geometry is in the order of 22cm long, which is electrically a very small object at lower frequencies.
  11. MOHAMED HAMDALLA liked a post in a topic by andries in Error when using FEKO solver for CMA   
    Hi Mohamed,
    I don't think I have a compatible version anymore.  If you run straight wire example.lua though, then the script should rebuild the model from scratch.  To run the script, just drag and drop it into CADFEKO and click on the run button.
  12. MOHAMED HAMDALLA liked a post in a topic by andries in Error when using FEKO solver for CMA   
    Hi Mohamed,
    Thanks for the model.  There are a few things that could explain why you're not seeing the characteristic modes in the attached model:
    The model doesn't contain any geometry.  There is only an infinite ground plane and a cable instance, both of which are approximations that can be used instead of complex geometry.  For characteristic modes, a model that will be solved using the Method of Moments (MoM) is needed.  In other words, there typically needs to be CAD that can be meshed into triangles and wire segments. The ports for the model are both Finite Element Method (FEM) line ports.  FEM is a separate solver from MoM and doesn't support characteristic mode analyses.  Neither port is excited or connected to anything. I recreated what I think the model is trying to do (see stright wire modified.cfx) using MoM.  Note that you need to add the requests that you are interested in; at the moment only the characteristic mode eigenvalue data is being calculated.
    Are you trying to reproduce results from an article/measurements/calculations?  Do you have any reference data?  Without further information, this is as far as I can go.  I would urge you to go through the Examples Guide and some overview documents on the website:
  13. MOHAMED HAMDALLA liked a post in a topic by JIF in Field to wire coupling   
    Hello Mohamed,
    I think the difference in the models comes down to the plane wave definition differences. I would suggest that you study the definition used to define the plane wave in thesis and then ensure that the correct plane wave is defined in FEKO. You can also model the simple cable model in MoM (in FEKO) directly and you will see that the results agree. The thesis is not perfectly clear w.r.t. dimensions and I see you have assumed the same radius and length as in previous sections.
    I hope this helps.
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