# multilayers lens

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Hello,

currently a student is trying to optimize a lens with multilayers for antennas.

He is using MLFMM to decrease the simulation time. Unfortunately the simulation is not finished for some reasons.

What can we do finish the simulation with less time?!?!?!?

Best Regards

Haj Hassan

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Hi Kuzi

You will need to use the FEM/MoM or FEM/MLFMM if the lens outer surface area is electrically large.

A FEM solution would be much more efficient. The concept is demonstrated in the 2 videos on altairuniversity.com at:
https://altairuniversity.com/learning-library/?type=learninglibraryitem&filter_resource_type=Training+Videos&filter_discipline=Electromagnetic&pg=3&search&filter_language&filter_source
Note there are 2 parts, as shown in the image. (Not sure why the 2nd part is being listed twice).

The horn will remain a pure MoM (or then MLFMM) solution, so you will only set the lens dielectric regions to FEM.

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Below is an image of the concept. Model the spheres with FEM (this will mesh tetrahedra) and the horn with MoM (surface triangles only).

If the dielectric wavelength of the outer sphere is much smaller than free space, then add an air layer (permittivity=1) so that the very outer surface of the spheres can be meshed with a surface element size of around lambda_freespace/8 to /10.

If the core of the spheres is not a solid, but free space (vacuum) then the principle of the previous paragraph applies as well. It might be better to use an air dielectric for the core, or rather keep as free space. It will depend on how large the core is, and the dielectric parameters of the first sphere. One of the two solutions will be computationally cheaper.

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Hello,

thank you very much.
It is working.

Best Regards

Haj Hassan

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