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How to add conductor losses to a CPWG?
Posted 3 oct. 2022, 13:02 UTC−4 Electromagnetics, RF & Microwave Engineering, Materials Version 6.0 4 Replies
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Hi! I am trying to add conductor losses to a simple coplanar waveguide model.
The model without losses (i.e. using PEC for all metals) works as expected (see attached "GCPWG_with_PEC_OK.mph").
However, when I try to replace the PEC on the signal trace with a "Transition Boundary Condition" to model conductor losses, I get the infamous error "Uniform lumped port should be placed between two conductive boundaries" on my ports (see attached "GCPWG_with_TBC_KO.mph").
I tried some suggestions I found googling (e.g. adding a domain with the trace material, so that the TBC can "attach" to it and derive its properties), but I still cannot solve this problem.
Could someone please help me to add conductor losses to this model?
Thanks and regards, Jorge.
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Consider applying an "impedance boundary condition" at the finite-conductivity surfaces, and remove the volumes of those domains from the computational space. If necessary, you can also use a short section of PEC that joins to the finite conductivity material. For materials like copper, do not mesh the interior of the material. You won't be computing fields inside it, for this kind of problem. Rather, use the impedance boundary conditiion to represent it as a surface with conductive losses.
-------------------Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
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Consider applying an "impedance boundary condition" at the finite-conductivity surfaces, and remove the volumes of those domains from the computational space. If necessary, you can also use a short section of PEC that joins to the finite conductivity material. For materials like copper, do not mesh the interior of the material. You won't be computing fields inside it, for this kind of problem. Rather, use the impedance boundary conditiion to represent it as a surface with conductive losses.
Thanks so much for your reply, Robert!
I tried to apply the impedance boundary condition to the signal trace, but I get the "not applicable" message (see attached). The model runs but from the results it's obvious the IBC it's being ignored and the conductor losses are not being modelled.
Could you please elaborate on how to apply this condition?
Regards, Jorge.
Attachments:
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Jorge,
the impedance boundary only works on external boundaries and it seems your lossy boundary is an internal one. I think you only need to assign a boundary material to the respective boundary and the transition boundary should work. A domain material assignment isn't working for boundaries.
Cheers Edgar
-------------------Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
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Thanks Edgard! Apparently it was indeed just a matter of properly selecting the boundaries fir the materials & TBC . The model now runs; I will go into analyzing the results to see if they make sense. Cheers, Jorge.