Problem with phase accuracy in waveguide polarisers

How to use openEMS. Discussion on examples, tutorials etc

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PaulUK
Posts: 76
Joined: Wed 28 Oct 2015, 14:23

Problem with phase accuracy in waveguide polarisers

Post by PaulUK » Sun 14 Jun 2020, 13:01

Does anyone know why it requires an extremely fine mesh to get sensible results when simulating various waveguide polarisers?
I'll post some examples when I get chance bit for square cross section corrugated polarisers I require about 80 to 100 cells per wavelength. For circular cross section waveguide I require over 300 cells per wavelength to get sensible results.

Two orthogonal port modes are being simulated and the S-parameters used to calculate the Axial ratio and differential phase.

This was going to be the basis for a polariser tutorial but the way things are going it wouldn't be practical with such huge meshes. Hope there is a solution to this issue. Thanks.

Hale_812
Posts: 171
Joined: Fri 13 May 2016, 02:54

Re: Problem with phase accuracy in waveguide polarisers

Post by Hale_812 » Mon 15 Jun 2020, 01:40

the answer is in your question. circular waveguide requires non-orthogonal meshing

thorsten
Posts: 1393
Joined: Mon 27 Jun 2011, 12:26

Re: Problem with phase accuracy in waveguide polarisers

Post by thorsten » Mon 15 Jun 2020, 07:39

This sound indeed a bit surprising, but maybe you can supply your script and we can have a look?

In which direction to you need this dense mesh. In all or only in direction of the waveguide or across the cross section?
Do you think that the stair-casing of the waveguide boundaries are the problem?
What value exactly are you looking at? Maybe there is a problem using the correct interpolations?

regards
Thorsten

PaulUK
Posts: 76
Joined: Wed 28 Oct 2015, 14:23

Re: Problem with phase accuracy in waveguide polarisers

Post by PaulUK » Mon 15 Jun 2020, 09:18

I shall post the examples that I have done and show their results either later or within a few days. I've just moved to Germany from the UK so things are a bit of a mess at the moment. As soon as I get my computer setup I will post what I have.

I previously did these simulations with CST and HFSS and the results converged well. So I used them as a reference or check that should be the aim of the openEMS simulations of the same structures. For the polariser tutorial I'd like to use openEMS off course.

Thanks.

PaulUK
Posts: 76
Joined: Wed 28 Oct 2015, 14:23

Re: Problem with phase accuracy in waveguide polarisers

Post by PaulUK » Mon 15 Jun 2020, 09:23

Hale_812 wrote:
Mon 15 Jun 2020, 01:40
the answer is in your question. circular waveguide requires non-orthogonal meshing
I've used the rectangular mesh with circular waveguide before, but I apply the appropriate circular waveguide port and had no problems.
I didn't use the cylindrical mesh because the slots in the waveguide walls of the polariser are not circular.

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