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Using symmetry with PML in RF Module

Posted 7 feb 2014, 10:47 GMT-5 RF & Microwave Engineering, Modeling Tools & Definitions, Parameters, Variables, & Functions Version 4.3 3 Replies

Bartek Chaber
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Hello,

My question is about possibility to utilize a symmetry in cases like in dipole antenna. The example model of halfwave dipole antenna from COMSOL models it without taking any symmetry into account, and I wonder why is it so?

I have tried to model only a half of the dipole from the example applying Perfect Magnetic Conductor boundary condition on the plane of the symmetry. But the radiation pattern is not correct so I must be missing something. Does PML should be modified or set up to allow the symmetry?

Regards,
Bartek Chaber
3 Replies Last Post 11 feb 2014, 10:12 GMT-5
Sergei Yushanov Certified Consultant
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Posted: 1 decade ago 10 feb 2014, 08:04 GMT-5
Bartek,

PMC is an appropriate boundary condition to account for symmetry plane. To get correct radiation pattern with symmetry plane, you need to impose the same symmetry boundary condition for the Far-Field Calculation: under Far-Field Domain>Far-Field Calculation node, check Symmetry in E (PMC) box and choose appropriate plane.

Attached is model for the dipole antenna with symmetry plane and comparison with analytical solution.

Best regards,
Sergei
Bartek, PMC is an appropriate boundary condition to account for symmetry plane. To get correct radiation pattern with symmetry plane, you need to impose the same symmetry boundary condition for the Far-Field Calculation: under Far-Field Domain>Far-Field Calculation node, check Symmetry in E (PMC) box and choose appropriate plane. Attached is model for the dipole antenna with symmetry plane and comparison with analytical solution. Best regards, Sergei
Bartek Chaber
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Posted: 1 decade ago 10 feb 2014, 17:54 GMT-5
Thank you very much Sergei!

I've downloaded your model, but I'm unable to open it because my version of COMSOL is too old, apparently. But I see your point and I've tried this approach.

Right now I'm plotting the E/H ratio on the surface with PMC applied and I see a different results than in the original, full model. Maybe there is no point in plotting it using this surface?

Best,
Bartek
Thank you very much Sergei! I've downloaded your model, but I'm unable to open it because my version of COMSOL is too old, apparently. But I see your point and I've tried this approach. Right now I'm plotting the E/H ratio on the surface with PMC applied and I see a different results than in the original, full model. Maybe there is no point in plotting it using this surface? Best, Bartek
Bartek Chaber
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Posted: 1 decade ago 11 feb 2014, 10:12 GMT-5
I've tried to recreate a dipole model with symmetry. To confirm that it is correct I've used E/H relation.
You can see the results attached. It can be seen that while the full model conforms the theory that a dipole should have stronger electric field in the near field which will reach a minimum and then increase towards the impedance of free space. I'm not sure how to interpret the results from the model with a symmetry.

If you want I can provide you with Java files with the simulations.

Best,
Bartek Chaber
I've tried to recreate a dipole model with symmetry. To confirm that it is correct I've used E/H relation. You can see the results attached. It can be seen that while the full model conforms the theory that a dipole should have stronger electric field in the near field which will reach a minimum and then increase towards the impedance of free space. I'm not sure how to interpret the results from the model with a symmetry. If you want I can provide you with Java files with the simulations. Best, Bartek Chaber

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