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2D Axisymmetric Solver - Coaxial TE11 mode

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Hello,

A few years ago, I was trying to use the 2D axisymetric solver to analyze the performance of a coaxial horn.

The coaxial horn has two ports: one cylindrical and one coaxial. I was surprized to notice that the 2D axisymmetric solver does not support the TE11 mode for the coaxial port or any other higher modes. Only the TEM mode which is useless. I tried to use the equations to analytically define the mode as indicated in the user manual and expected to work.

Alas that also did not work either.

I was wondering if the latest version does support the TE11 mode.

Thank you


5 Replies Last Post Aug 23, 2023, 6:32 p.m. EDT
Dave Greve Certified Consultant

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Posted: 8 months ago Aug 23, 2023, 2:05 p.m. EDT
Updated: 8 months ago Aug 23, 2023, 2:05 p.m. EDT

The circular TE11 mode is not axially symmetric, so of course it cannot be modeled as 2D axisymmetric.

The circular TE11 mode is not axially symmetric, so of course it cannot be modeled as 2D axisymmetric.

Robert Koslover Certified Consultant

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Posted: 8 months ago Aug 23, 2023, 2:53 p.m. EDT
Updated: 8 months ago Aug 23, 2023, 2:53 p.m. EDT

Dave Greve is correct (of course) about the TE11 mode not being axially-symmetric. However, Comsol Multiphysics will support a rather clever combination of a 2D axi-symmetric model with an analytic assumption about the azimuthal dependence of the fields. You can learn all about this method from the supplied Application Library example at https://www.comsol.com/model/corrugated-circular-horn-antenna-15677 . I believe you should be able to adapt this approach to your problem. Good luck.

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Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
Dave Greve is correct (of course) about the TE11 mode not being axially-symmetric. However, Comsol Multiphysics will support a rather clever *combination* of a 2D axi-symmetric model with an *analytic* assumption about the azimuthal dependence of the fields. You can learn all about this method from the supplied Application Library example at https://www.comsol.com/model/corrugated-circular-horn-antenna-15677 . I believe you should be able to adapt this approach to your problem. Good luck.

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Posted: 8 months ago Aug 23, 2023, 4:43 p.m. EDT
Updated: 8 months ago Aug 23, 2023, 5:12 p.m. EDT

TICRA has a similar body of revolution (2D Axisymmetric) solver. They were probably aware that having the TEM will make the solver unusable so they provided the right option for port definitions.

The corrugated horn example does not address my problem.

TICRA has a similar body of revolution (2D Axisymmetric) solver. They were probably aware that having the TEM will make the solver unusable so they provided the right option for port definitions. The corrugated horn example does not address my problem.

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Posted: 8 months ago Aug 23, 2023, 4:45 p.m. EDT
Updated: 8 months ago Aug 23, 2023, 5:15 p.m. EDT

Dave Greve is correct (of course) about the TE11 mode not being axially-symmetric. However, Comsol Multiphysics will support a rather clever combination of a 2D axi-symmetric model with an analytic assumption about the azimuthal dependence of the fields. You can learn all about this method from the supplied Application Library example at https://www.comsol.com/model/corrugated-circular-horn-antenna-15677 . I believe you should be able to adapt this approach to your problem. Good luck.

I did and COMSOL crashed. Had my equations checked by several people and found OK.

>Dave Greve is correct (of course) about the TE11 mode not being axially-symmetric. However, Comsol Multiphysics will support a rather clever *combination* of a 2D axi-symmetric model with an *analytic* assumption about the azimuthal dependence of the fields. You can learn all about this method from the supplied Application Library example at https://www.comsol.com/model/corrugated-circular-horn-antenna-15677 . I believe you should be able to adapt this approach to your problem. Good luck. I did and COMSOL crashed. Had my equations checked by several people and found OK.

Robert Koslover Certified Consultant

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Posted: 8 months ago Aug 23, 2023, 6:32 p.m. EDT
Updated: 8 months ago Aug 23, 2023, 6:31 p.m. EDT

Hmm. Not sure what caused it to crash. I've used the example method successfully, but it does take some attention to detail. Anyway, you might want to consider posting your .mph file to the forum or even contacting Comsol Support directly, since the Comsol folks are usually interested in fixing any condition that would tend to crash the software (that is, as opposed to simply generate an error message). Error messages (due to error causing conditions) are to be expected now and then; crashes are not.

-------------------
Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
Hmm. Not sure what caused it to crash. I've used the example method successfully, but it does take some attention to detail. Anyway, you might want to consider posting your .mph file to the forum or even contacting Comsol Support directly, since the Comsol folks are usually interested in fixing any condition that would tend to crash the software (that is, as opposed to simply generate an error message). Error messages (due to error causing conditions) are to be expected now and then; crashes are not.

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.