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Port settings with normal component fields (possibly a bug)

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Hello,

I am trying to simulate a structure with oblique incidence. From the port settings, I have noticed a possible bug in COMSOL.

Please take a look at the attached screenshots: for all other settings identical, if I setup the port with the magnetic field, it works well. However, when I setup the port with the electric field, I get errors where the port doesn't function as it should. Note that this is 2D simulation where the port is parallel to the x-axis, and I am simulating a TM case. I can simply use the H-field in the port settings, but I think E-field setting should work as well. There are instances where I launch a mode that is neither TE nor TM with respect to the port in 3D simulations.

My guess is that whenever there is a field component perpendicular to the port surface in the port settings (y-component in this case), the port doesn't function well: this is the electric field case.

I am not sure if I am mistaken or this is a limitation of COMSOL.

Thanks.
Young Mo


2 Replies Last Post 12 juil. 2016, 08:29 UTC−4
Robert Koslover Certified Consultant

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Posted: 1 decade ago 28 nov. 2013, 21:19 UTC−5
My own approach, which has worked well for me in a number of versions of Comsol Multphysics, is to specify ports using only purely tangential fields. That should let you specify any TE or TM mode, using tangential E or tangential H fields, respectively. I haven't tried specifying two modes (both TE and TM) at once as a boundary condition, so I guess that is an interesting question.
My own approach, which has worked well for me in a number of versions of Comsol Multphysics, is to specify ports using only purely tangential fields. That should let you specify any TE or TM mode, using tangential E or tangential H fields, respectively. I haven't tried specifying two modes (both TE and TM) at once as a boundary condition, so I guess that is an interesting question.

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Posted: 8 years ago 12 juil. 2016, 08:29 UTC−4
Hello,

I am finding the same problem when I want to have an excitation at a port that is a mixture of TE and TM modes. Has anyone else encountered/solved this problem?

Luca
Hello, I am finding the same problem when I want to have an excitation at a port that is a mixture of TE and TM modes. Has anyone else encountered/solved this problem? Luca

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