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Simulating a resonant cavity

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Hi
I want to simulate my tapered cone cavity to obtain a resonant frequency of that. I made a project but I can't compute that. There are some errors. I attach a project file.



3 Replies Last Post 05.12.2016, 14:31 GMT-5
Sergei Yushanov Certified Consultant

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Posted: 8 years ago 28.11.2016, 13:11 GMT-5
Jakub,

There are several issues with your model:

1. You are trying to find resonant frequency for metal-filled cavity, which doesn't make much sense. Remove Copper domain material and add air domain material instead-this would give you air-filled cavity without losses.
2. Active port cannot be used in Eigenfrequency analysis -disable Port BC.
3. Increase Desired number of eigenfrequencies because several first modes might be spurious.
See attached file "Untitled_sy_no_losses.mph".

If you want to account for metal wall losses, then:
1. Add Copper material, change Geometric entity level to "Boundary" and select all exterior boundaries.
2. Apply Impedance Boundary Condition to all exterior boundaries of the cavity.
3. Impedance BC accounts for frequency-dependent losses and this makes eigenvalue problem nonlinear.
4. When solving nonlinear eigenvalue problem, it is necessary to provide initial guess for eigenfrequency and linearization point - you can do this under Eigenvalue Solver 1/Transform point.
See attached file "Untitled_sy_with_losses.mph".

Regards,
Sergei
Jakub, There are several issues with your model: 1. You are trying to find resonant frequency for metal-filled cavity, which doesn't make much sense. Remove Copper domain material and add air domain material instead-this would give you air-filled cavity without losses. 2. Active port cannot be used in Eigenfrequency analysis -disable Port BC. 3. Increase Desired number of eigenfrequencies because several first modes might be spurious. See attached file "Untitled_sy_no_losses.mph". If you want to account for metal wall losses, then: 1. Add Copper material, change Geometric entity level to "Boundary" and select all exterior boundaries. 2. Apply Impedance Boundary Condition to all exterior boundaries of the cavity. 3. Impedance BC accounts for frequency-dependent losses and this makes eigenvalue problem nonlinear. 4. When solving nonlinear eigenvalue problem, it is necessary to provide initial guess for eigenfrequency and linearization point - you can do this under Eigenvalue Solver 1/Transform point. See attached file "Untitled_sy_with_losses.mph". Regards, Sergei


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Posted: 8 years ago 28.11.2016, 16:30 GMT-5
Thank you for reply.
Can you show me what I should do to simulate wall losses? Where are results? I don't know how to do that. Should I add at results at electric field a surface and set surface losses?
Where can I see which mode I am operating at each eigenfrequency and which mode is dominant?
Thank you for reply. Can you show me what I should do to simulate wall losses? Where are results? I don't know how to do that. Should I add at results at electric field a surface and set surface losses? Where can I see which mode I am operating at each eigenfrequency and which mode is dominant?

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Posted: 8 years ago 05.12.2016, 14:31 GMT-5
Hi
Can somebody tell me how can I obtain the operating mode? I try to do this, but I don't see there any options about that.
Hi Can somebody tell me how can I obtain the operating mode? I try to do this, but I don't see there any options about that.

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