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problem in assigning port to a co-planar waveguide

Posted Nov 1, 2011, 2:19 a.m. EDT RF & Microwave Engineering Version 4.2 3 Replies

Glenston Miranda
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Hi

I'm working on a very simple co-planar waveguide. I'm finding it hard to assign a port to it.
I've tried different combinations but none are working effectively. The dielectric is made up off
quartz and the dimensions are chosen to produce characteristic impedance of 50 ohm.

I'm attaching the model that i created in this post .
Please have a look and try posting your suggestions.

Thanks a lot for your time and effort!!!

Regards
Glenston

Attachments:

3 Replies Last Post Nov 1, 2011, 2:48 p.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Nov 1, 2011, 4:11 a.m. EDT
Hi

the ports are to be placed where you enter the energy, typically on a conductor entry (probably in the central lateral block side in your case.

But what puzzles me more, I'm not RF specialist, but still for me one need to model also some surrounding "vacuum" to be sure the fields can loop freely around. In EM the field propagate everywhere and you need to describe this too. So I would surround your region by a cube or a sphere (and consider layers + infinite elements to keep the volume small) or possibly consider some symmetry boundaries to further reduce the model size if you have RAM problems. RF require a lot of elements to catch the short wavelength.

In certain cases you can also replace a large volume by some clever boundary conditions, nt sre it's possible n your case.

--
Good luck
Ivar
Hi the ports are to be placed where you enter the energy, typically on a conductor entry (probably in the central lateral block side in your case. But what puzzles me more, I'm not RF specialist, but still for me one need to model also some surrounding "vacuum" to be sure the fields can loop freely around. In EM the field propagate everywhere and you need to describe this too. So I would surround your region by a cube or a sphere (and consider layers + infinite elements to keep the volume small) or possibly consider some symmetry boundaries to further reduce the model size if you have RAM problems. RF require a lot of elements to catch the short wavelength. In certain cases you can also replace a large volume by some clever boundary conditions, nt sre it's possible n your case. -- Good luck Ivar
Glenston Miranda
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Posted: 1 decade ago Nov 1, 2011, 1:16 p.m. EDT

Hi

the ports are to be placed where you enter the energy, typically on a conductor entry (probably in the central lateral block side in your case.

But what puzzles me more, I'm not RF specialist, but still for me one need to model also some surrounding "vacuum" to be sure the fields can loop freely around. In EM the field propagate everywhere and you need to describe this too. So I would surround your region by a cube or a sphere (and consider layers + infinite elements to keep the volume small) or possibly consider some symmetry boundaries to further reduce the model size if you have RAM problems. RF require a lot of elements to catch the short wavelength.

In certain cases you can also replace a large volume by some clever boundary conditions, nt sre it's possible n your case.

--
Good luck
Ivar

Hi

thanks a lot for your reply.
I will definitely surround it with air.
Assigning the port is an issue. Lumped port needs to be connected between perfect electric conductors.
As per your suggestion if i chose the central lateral block placed on the dielectric then it shows an error in comsol.
Is there any other port condition that i can use ?

Regard
Glen

[QUOTE] Hi the ports are to be placed where you enter the energy, typically on a conductor entry (probably in the central lateral block side in your case. But what puzzles me more, I'm not RF specialist, but still for me one need to model also some surrounding "vacuum" to be sure the fields can loop freely around. In EM the field propagate everywhere and you need to describe this too. So I would surround your region by a cube or a sphere (and consider layers + infinite elements to keep the volume small) or possibly consider some symmetry boundaries to further reduce the model size if you have RAM problems. RF require a lot of elements to catch the short wavelength. In certain cases you can also replace a large volume by some clever boundary conditions, nt sre it's possible n your case. -- Good luck Ivar [/QUOTE] Hi thanks a lot for your reply. I will definitely surround it with air. Assigning the port is an issue. Lumped port needs to be connected between perfect electric conductors. As per your suggestion if i chose the central lateral block placed on the dielectric then it shows an error in comsol. Is there any other port condition that i can use ? Regard Glen
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Nov 1, 2011, 2:48 p.m. EDT
Hi

you can only assign a port on a boundary of a domain included in your physics, you have NOT included the metal parts ;)

--
Good luck
Ivar
Hi you can only assign a port on a boundary of a domain included in your physics, you have NOT included the metal parts ;) -- Good luck Ivar

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