Crosstalk

Zakaria
Zakaria Altair Community Member
edited October 2020 in Community Q&A

Hi all,

I am trying to simulate crosstalk between wires. I have used both the cable wires and normal wires with ports( both attached). I am not sure why i am not getting any crosstalk (voltage at wire 2 ends) for the cable setup. While i am getting some voltage on the other setup. However, the voltage I am getting from setup 2 doesn't match with CST results (voltage average is -20 dB). I am not sure which setup is more accurate to model the crosstalk between two wires (wire 1 connected from one end to VNA and the other end connected to SMA load resistor, Wire 2 both ends terminated by SMA resistors. ). Thanks

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Answers

  • Torben Voigt
    Torben Voigt Altair Community Member
    edited October 2018

    Hi Mohamed,

     

    For multiple cable instances within one CableHarness only capacitive / inductive coupling effects will be taken into account. It cables have a certain distance these effects will be zero and and only coupling via field strength will be present. To take into account coupling due to radiation, the cables must be in seperate CableHarnesses, see attached

     

    Here's the comparison between wires and cables:
    <?xml version="1.0" encoding="UTF-8"?>image.thumb.png.bf3ed1a7f6403ace828b4fe6bd61a656.png

    <?xml version="1.0" encoding="UTF-8"?>image.png

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  • Zakaria
    Zakaria Altair Community Member
    edited October 2018

    @Torben Voigt Thanks a lot. However, do you have any explanation for the disagreement between the two ways? Also is it a good way to simulate the experiment mentioned previously or there I another way to get s21 results rather than the voltage in this case. I am mentioning this because CST-Cable Studio shows completely different values and they are also using MTL and the values are quite similar to the measured values.

    Thanks

    image.png.9785f6de80655e806b48e0dcbe7d5daf.png

  • Torben Voigt
    Torben Voigt Altair Community Member
    edited October 2018

    Hi @MOHAMED HAMDALLA,

     

    The difference can be explained by the differet methods. While the MoM (crosstalk2.cfx) takes into account all possible effects in the scenario,  the Multi Transmission Line Theory (crosstalk_alt.cfx) is obviously an approximation. The MTL is extremely useful for complex cable harness, possibly different kinds of shielding included, complex cable bundles in an electrically large environment (e.g. car), etc.

     

    S-parameters for cable ports in FEKO are not yet supported, but planned for 2019. For simple scenarios like this, I would recommend using MoM, where you can use an SParameterConfiguration to get S21 directly.

     

    One question about the picture in your last post: The frequency is given in Hz, is that correct?

  • Zakaria
    Zakaria Altair Community Member
    edited October 2018

    Thank you for your help.

    Sorry, It is in GHz.

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