Warning message: The ratio of the segment radius to length is too large

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

The dimension of the probe of the coaxial cable it is constant and it 0.65mm, but FEKO considered this value as abnormal and he sent worming message 
How we should react regards this message do we ignore it?
Thanks in advance 
 

<?xml version="1.0" encoding="UTF-8"?>Warning message.jpg

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Answers

  • Johan_Huysamen
    Johan_Huysamen
    Altair Employee
    edited January 2018

    Hi gheit

     

    When modeling wires with the default Method of Moments (MoM) in FEKO the 'thin wire approximation' is used. This requires that the wire segments have a radius significantly smaller than the length of the segments. You would therefore see this warning when your wires either have large radii or are very short.

     

    When feeding an antenna with a wire pin, the radius of the pin would affect its inductance and it is therefore recommended to always use the actual physical radius (as you have done here). If this leads to the above warnings you should consider replacing the wire with a cylinder (meshed into surface triangles). This could then be excited by either an edge port or a waveguide excitation (which would be the recommended option for a coaxial feed).

     

    Regards,

    Johan H

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2018

    do you have in your hand similar example to feed patch antenna with probe and using cylinder instead of wire

    thanks

  • JIF
    JIF
    Altair Employee
    edited January 2018

    You can have a look at 'A.12 Dielectric Resonator Antenna on Finite Ground' in the FEKO example guide for an example where a pin was used with a waveguide / modal port feed. For the edge port, I don't have an example readily available.

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