Spherical shells don't work correctly

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Moderators: thorsten, sebastian

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teepegg
Posts: 5
Joined: Tue 11 Dec 2012, 06:27

Spherical shells don't work correctly

Post by teepegg » Tue 11 Dec 2012, 06:38

I found out that AddSphericalShell doesn't correctly create a spherical shell, instead, it seems to neglect clearing the inside of the shell. Additionally, the documentation in AddSphericalShell.m is ambiguous as to whether the inner or outer radius of the shell is specified. Of course, the workaround is trivial; just use AddSphere to make a sphere of the desired material, then again with the background material (usually air) with a smaller radius.

That aside, openEMS is wonderful! Thank you so much!

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

Re: Spherical shells don't work correctly

Post by thorsten » Tue 11 Dec 2012, 10:39

Hi,

thanks for the feedback.

How did you check the spherical shell does not work? I think it is not displayed correctly in AppCSXCAD but I think it should work correctely in openEMS.
Sebastian recently fixed the representation of a cylindrical shell in AppCSXCAD (it worked fine in openEMS).
I will have a look into it.

regards
Thorsten

teepegg
Posts: 5
Joined: Tue 11 Dec 2012, 06:27

Re: Spherical shells don't work correctly

Post by teepegg » Wed 12 Dec 2012, 05:27

I noticed that the sphere had a very dramatic effect on antenna patterns and impedance, which I did not expect from a shell much thinner than a wavelength. So I used a dump box to visualize the fields and saw a distinct, large dielectric waveguide mode in the sphere. When I switched to using two spheres, the effect disappeared.

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

Re: Spherical shells don't work correctly

Post by thorsten » Wed 12 Dec 2012, 17:37

Hi,

well yes, there was a bug. A very obvious one, so it was quick to fix it.
And it seems nobody so far has tried a spherical shell or the bug would have been reported earlier... I hope...

In the matlab interface function AddSphericalShell a 'Sphere' instead of a 'SphericalShell' is been created... so it is easy to fix in older version for everyone.
Of course it will be fixed in the next release (v0.0.30). I have attached the fixed version as well, just replace it.

In AppCSXCAD the shell now will not being displayed since there is no vtk method to draw such a shell. This will be added in v0.0.30 as well.

I added a note about the inner vs outer radius as well:
% Note:
% the inner radius of this shell is rad-shell_width/2
% the outer radius of this shell is rad+shell_width/2
regards
Thorsten
Attachments
AddSphericalShell.m
bug fixed version of AddSphericalShell, will be included in openEMS version 0.0.30
(1.16 KiB) Downloaded 553 times

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