Excitation of a CPW on infinite substrate

Altair Forum User
Altair Forum User
Altair Employee
edited November 2020 in Community Q&A

Hello,

I am trying to obtain the S-parameters of CPW line on an infinite substrate by calculating magnetic current rather than electrical current. I am using edge ports to achieve the results. However, my results are not correct. I have attached the layout for reference.  Does anyone know how to resolve this issue? I am thinking that this is occurring due incorrect port definition but not sure.

 

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Answers

  • Johan_Huysamen
    Johan_Huysamen
    Altair Employee
    edited April 2017

    Hi N_vasan

     

    It is not exactly clear from your image how the feed section and edge port is defined so I am unable to comment on this.

     

    For a simple way of feeding such a model, I would suggest using a wire 'bridge' across a gap as in the attached image. Here the wire bridges over the gap - connecting the two sections of the PEC layer. a wire port is then applied to this wire. The same is then done at the other end of the CPW section.

     

    Regards,

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

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited April 2017

    Hi Johan

    I tried initially with wire port as you have suggested. However, the S-parameter values were not as expected. I am expecting S11 around -30dB, S21 < -1dB and a port impedance of 50 ohms. These values are obtained from HFSS simulations. However, when using the port or edge port along with Green's function I am getting S11 around -15dB and S21 around -0.48 dB at lower frequencies, -0.28dB at higher frequencies, and a port impedance of 1ohms to 5ohms. 

    I am unable to understand the reason for inaccurate results. Could you guide me?

    Thank you

     

     

  • Johan_Huysamen
    Johan_Huysamen
    Altair Employee
    edited May 2017

    Dear N_vasan

     

    Could you please share your FEKO model (CADFEKO CFX file)?

     

    Regards,

    Johan H

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited November 2020