2 identical cables with very different results

Claudio Aguiar
Claudio Aguiar Altair Community Member
edited July 2023 in Community Q&A

Hello I am trying to simulate cross-talk between 3 wires using FEKO/cables. I am doing this in 2 different ways: (1) I define 3x wire cross-section (single conductor), I define 3x cable instances, one for each wire, all taking same path; (2) I define 3x wire cross-sections (single conductor) but place all them inside a single BUNDLE, then I define a single cable instance for the bundle.  I have confirmed the 2 approaches have the exact same geometry and mediums/materials, etc. The only difference is that one uses a BUNDLE and the other does not. The outcomes of both simulations are completely different. Is there any ´possible explanation why this would happen?

Answers

  • GGAMPALA
    GGAMPALA
    Altair Employee
    edited July 2023

    May be you used the auto bundle option which can result in the cables not arranged in the same way as they are when modeled individually. So, try disabling the auto bundle option and specify the positions of each cables to represent the same arrangement like individual cables.

  • Claudio Aguiar
    Claudio Aguiar Altair Community Member
    edited July 2023

    Thank you for your response. Here is the geometry for both simulations. Although I do not have direct control over the position of the wires in the case of 3x single conductors, I pressed the "rearrange cross-sections" button 100 times until the wires were disposed in the same position as in the wire bundle case. By the way, I suspect that the exact (x, y) position of the wires in the bundle has no effect on the simulation results, as long as the relative position is maintained, per the outcome of some trial-and-error investigations, at least wrt cross-talk MTL.

    I assure you all dimensions and mediums are the same (everything is free-space and I have tried different configurations of the bundle, they all have same results which are different between single conductors versus cable bundle).

    case#1 - cable bundle

    image

    case #2 - 3 x single conductor

    image

    The results are very different as you can see

    Case #1 - results

    image

     

    case # 2 - results

    image

    It looks like there are many different ways of assembling the same harness and there is no direction on the best way to do it in the User Guide, but in these examples, I have used the same base file and just added the bundle, so everything else is exactly the same. Here is the schematic:

    image

  • GGAMPALA
    GGAMPALA
    Altair Employee
    edited July 2023

    I would recommend to submit a support ticket in AltairOne and share your model for further investigation:

    Altair One