EEVblog Electronics Community Forum
Electronics => RF, Microwave, Ham Radio => Topic started by: KlausKragelund on July 09, 2024, 07:29:15 am
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Hi
I am working on a project, where large currents are running on cables inside a cabinet. We are exceeding the radiated EMI limits.
So I am looking for a way to determine the impact on moving cables around, and the impact of the shielding effectiveness of the cabinet enclosure, for example distance between screws that fix the cover plates to the cabinet.
I have very little experience with OpenEMS, Ansys seems to have an easier flow, but cannot afford Ansys tools.
Is it possible, and if so, how hard is it to do a layout of placement of cables, define a current waveform in the cables, and then getting results that could correlate to a 3m measurement in an anechoic chamber?
Thanks
Klaus
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If you have necessary equipment, it may be faster to do shielding effectiveness tests on the prototype for a single project. It will take time to have satisfactory results with openEMS. But it can be helpful if you are doing this occasionally.
I don't know how to define current waveforms. But for the cable design you can use FreeCAD to do the layout. There is a good project in the below link to show you the steps from 3D design to EMS simulation:
https://github.com/toammann/Multilayer_SMA2Microstrip (https://github.com/toammann/Multilayer_SMA2Microstrip)
You can enter dimension parameters into spread sheets in FreeCAD. For example you can define variables like "cable_length" or "screw_spacing" in the table, then export your geometry to openEMS and do simulation. Then you edit the "screw_spacing" in FreeCAD and it will update all 3D design with the new parameter. Then you can export and simulate again.
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If you have necessary equipment, it may be faster to do shielding effectiveness tests on the prototype for a single project. It will take time to have satisfactory results with openEMS. But it can be helpful if you are doing this occasionally.
I don't know how to define current waveforms. But for the cable design you can use FreeCAD to do the layout. There is a good project in the below link to show you the steps from 3D design to EMS simulation:
https://github.com/toammann/Multilayer_SMA2Microstrip (https://github.com/toammann/Multilayer_SMA2Microstrip)
You can enter dimension parameters into spread sheets in FreeCAD. For example you can define variables like "cable_length" or "screw_spacing" in the table, then export your geometry to openEMS and do simulation. Then you edit the "screw_spacing" in FreeCAD and it will update all 3D design with the new parameter. Then you can export and simulate again.
That is an excellent find.
I also agree with the author on this:
Unfortunately, openEMS lacks detailed training materials what makes the software hard to use for a beginner.
So much potential squandered by the lackluster documentation.
But writing it and maintaining it is a thankless job. So very understandable that there is not that much of it.
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Thank you for the comments and the excellent link
With respect to documentation, OpenEMS has great potential and if it was easier to use, some companies could use OpenEMS instead of Ansys. Some kind of donation could be good to keep the project going...