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How do I use Layers in Geometry definition?

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I am working with the Dipole Antenna example and can't understand the use of Layers. The help menu has following information:

Layers

Layers can be used to create sandwich primitives by adding layers on one or more sides. You specify the thicknesses of layers in the Layers table, and optionally a name for each layer. The outermost layer comes first. Select the check boxes to specify where to apply the layers.

In the example the Layer Thickness should be the length of the half dipole (in this case 1m) followed with the information 'The domain inside the antenna radiators is not part of the model analysis'.
If the Layer Thickness would be e.g 0.02mm or would be 0 with a surface resistance it would make sense but with 1m I don't get it.

I searched for an example how to use this Layer option but I couldn't find one. If someone could point me in the right direction this would be nice.

2 Replies Last Post 10 févr. 2017, 22:17 UTC−5
Magnus Ringh COMSOL Employee

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Posted: 7 years ago 7 févr. 2017, 10:24 UTC−5
Hi,

Layers are available as a tool for creating geometries in COMSOL Multiphysics. It is intended for creation of (thin) layers, but there is nothing that prevents you from using it like in this example, where the top and bottom layers of the cylinder define the cylindrical arms above and below a small voltage source in between. It would have been possible to create the geometry using three separate cylinders instead, but using layers it is easy to construct a symmetric layout. Then, by subtracting the cylinder, only its exterior boundaries remain in the model, so the comment that "The domain inside the antenna radiators is not part of the model analysis" really refers to the next step in the geometry creation (using the Difference node).

Best regards,
Magnus Ringh, COMSOL
Hi, Layers are available as a tool for creating geometries in COMSOL Multiphysics. It is intended for creation of (thin) layers, but there is nothing that prevents you from using it like in this example, where the top and bottom layers of the cylinder define the cylindrical arms above and below a small voltage source in between. It would have been possible to create the geometry using three separate cylinders instead, but using layers it is easy to construct a symmetric layout. Then, by subtracting the cylinder, only its exterior boundaries remain in the model, so the comment that "The domain inside the antenna radiators is not part of the model analysis" really refers to the next step in the geometry creation (using the Difference node). Best regards, Magnus Ringh, COMSOL

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Posted: 7 years ago 10 févr. 2017, 22:17 UTC−5
Hi Magnus,

Thank you for the replay.

OK. In this example was used an advance technique to create the dipole. Why isn't there any explanation why this was done in this way and/or without any pictures in the documentation. To figure this task out I have to do it on my own. Only reading isn't sufficient because in the step to step instruction isn't any explanation why I am doing it for what reason.

Best regards,
Stefan
Hi Magnus, Thank you for the replay. OK. In this example was used an advance technique to create the dipole. Why isn't there any explanation why this was done in this way and/or without any pictures in the documentation. To figure this task out I have to do it on my own. Only reading isn't sufficient because in the step to step instruction isn't any explanation why I am doing it for what reason. Best regards, Stefan

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