STR file currents

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

Good day,

 

Some people have suggested using a str2ascii utility to properly access the STR file. My understanding is that the str2ascii utility does no longer exist and there's a function integrated to FEKO to replace it. I'm using FEKO 7.0.2, and I am wondering if someone can teach me how to read the STR file.

 

In the quote below @RenierM  briefly mentioned STR file contains 'matrix solution coefficients' - what exactly is this? Is this the currents matrix in the MoM matrix equation [Z] = [V] ? what is the difference between the currents from the STR file and those from the OS file? My guess is the currents from OS file are obtained before applying certain expansion function such as RWG, and the currents from the STR file are after applying the expansion function.

 

Thank you in advance for answering my questions.

 

Shane

 

Altair Forum User said:

The values exported to the STR-file can be accessed using the str2ascii tool, located at http://www.feko.info/support/helpcenter/how-to/how-to-read-the-.mat-.lud-.rhs-files-and-.str-files

 

The values exported to the STR-file are the matrix solution coefficients - if RWG basis functions are used the values correspond to the currents on the triangles. 

 

If you solve the CMA eigen equation using the matrix (which you exported above), you will calculate the eigen vector which in the case of RWG-basis functions then correspond to the eigen current. 

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Answers

  • Wilco Strydom
    Wilco Strydom New Altair Community Member
    edited November 2018

    Hi Shane,

     

    The str2ascii utility is still being supported and maintained and would be the approach to take if you are looking to access the solution vector.
    The MoM matrix equation has a current vector (not matrix) that can be written to a *.str file and reused for further simulations where the model is not changed but more requests are added for instance. This *.str file is thus the coefficients of the expansion functions. The *.os file contains samples of the expanded surface current. This also represents the values that you are able to plot in POSTFEKO.

    Note that you are on a very old version of Feko, and this might complicate certain support questions a bit.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited November 2018

    Hi @Wilco Strydom

     

    Thank you very much for your detailed explanation on the types of current vector in the .str file. However, could you please provide a link for the str2ascii utility? I can't find a working url link where the utility can be downloaded. 

     

    Another question is, would FEKO be able to read an existing current file with user defined current data - either .str or .os and calculate the far-zone electric fields accordingly? If so, please advise me the procedures to follow. 

     

    Thank you,

    Shane

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited November 2018

    Can someone please answer my above questions? Or an official FEKO support email address would be much appreciated!

     

    Thanks in advance!

  • Mel
    Mel Altair Community Member
    edited November 2018

    Hi Shane


    The str2ascii.exe is part of the FEKO 2018 installation. See the bin folder of FEKO.

     

    See the UserManual.pdf in the help folder also for further details. Attached an image for your convenience.

    FEKO can read back in the *.str files but not *.os files.

     

    <?xml version="1.0" encoding="UTF-8"?>str2ascii.png

     

    Run a model with export to *.str file set (Save/Read currents in Solver settings)

    • Run 'str2ascii <filename.str> -r > ascii.str' and get a file 'ascii.str' with an ASCII format of the *.str
      file which Feko can read again.
    • Keep structure of this *.str file (header, MD5 checksums etc.), but replace coefficients with user defined ones.
    • Rename to main project name and change the from export to import of the *.str file, with *.str file the same name as the new project name.
    • Then run Feko again where you can request a far field..
  • Madelé
    Madelé
    Altair Employee
    edited November 2018

    Or an official FEKO support email address would be much appreciated!

     

    Hello Shane

     

    I trust Mel's answer provided the answers you were looking for. If you need the support information in future, you can open the Feko or HyperWorks documentation and look for 'Technical Support'. You will find a list of support e-mail addresses.

     

    Alternatively, visit Altair Connect (from the HyperWorks website, https://altairhyperworks.com/, Support & Training menu or directly at https://connect.altair.com/), go to Contact Support and select your country:

    image.pngimage.png

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