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Multimode S-parameters

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I'm using RF module in 3d and I need to compute a generalized scattering matrix of a waveguide structures. The ports are of arbitrary shape and modes must be computed numerically. But when I add a port with numerical modes, there is no way to choose how many modes one should solve for. You can set the power but not what mode should be excited with that power. I could not therefore compute the multimode generalized scattering matrix.
Note that when you set up a boundary mode problem, you can choose the number of modes, but I don't know how to transfer that info to the physical structure so as to compute the GSM.
I'm surely missing something. I've read through the examples and the manual, but the only info was how to compute the single-mode scattering matrix s11, s12, s21, s22. In my case, all these parameters are submatrices.
Any help?
Thanks in advance
Guido

1 Reply Last Post 11 janv. 2012, 01:43 UTC−5

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Posted: 1 decade ago 11 janv. 2012, 01:43 UTC−5
Thanks Guido for asking this problem . Actually I'm also facing the same problem as you . Well as we know numeric port comes in to the use when we do not know the eigenmode pattern . My question : When we do mode analysis for 2D cross section of waveguide , we need to give desired number of modes , search for modes around , transform and mode analysis frequency . By giving that information we can easily have the list of propagating and non propagating modes .But same thing we do not get for 3D structure using numeric port . Please tell me how we can have list of eigenmodes for arbitrary shape .



With Best Regards
R.k.J
Thanks Guido for asking this problem . Actually I'm also facing the same problem as you . Well as we know numeric port comes in to the use when we do not know the eigenmode pattern . My question : When we do mode analysis for 2D cross section of waveguide , we need to give desired number of modes , search for modes around , transform and mode analysis frequency . By giving that information we can easily have the list of propagating and non propagating modes .But same thing we do not get for 3D structure using numeric port . Please tell me how we can have list of eigenmodes for arbitrary shape . With Best Regards R.k.J

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