Warning in feko
Altair Employee
Answers
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Hello azlanthetypewritter
It looks like you are simulating at a very low frequency and at low frequencies the standard formulation breaks down (big difference in the scalar and vector potential components and when they are added, the smaller value could be completely lost and thus lead to incorrect results). If you are not using any dielectric materials (all PEC), then you can turn on low frequency stabalisation (see the solution settings). If your model does contain dielectric materials, these will have to use VEP instead of SEP, since VEP is more stable at low frequencies. You could also try just using double precision instead of the default single precision (also on the Solution Settings dialog).
I hope that helps!
Kind regards
JIF
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thank you.. it works.
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hello jif.
i got another error.. this time on running solver.
actually i am trying to run shielding analysis on radio car. so i set up the material Polystyrene(plastic) but the back housing is metal (PEC)
as the picture below.
i really appreciate your help. thank you
<?xml version="1.0" encoding="UTF-8"?>
<?xml version="1.0" encoding="UTF-8"?>
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Hello azlanthetypewritter,
It looks like you ran out of memory (and disk space) for the out of core solution. The first question is, is the dielectric important for the shielding tests? I would imagine that the car radio has metal on all 6 sides, but has plastic over the metal on the one side. If that is the case, I don't think the dielectric is important and you could find a solution that fits on your machine and is faster by just looking at the PEC model.
What is the minimum shielding that you want to simulate? With EFIE you will only be able to go down to about -60 dB. At higher frequencies there are 'tricks' to make it more accurate, but with low frequency stabilisation those tricks won't work.
Are you able to submit the model so that I can take a closer look?
Kind regards
JIF
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actually i try to run 3 type of housing. seem i encounter many error. i beginner in this shielding (EMC) field.
i using FEKO v14.0.430
i attach the model for you to see.
Really appreciated if you can help me.
thanks
A
<?xml version="1.0" encoding="UTF-8"?>
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I had a look at your models. I think they are meshed too fine (more than required). You should be able to just use standard meshing. At 125 kHz, the wavelength is very large relative to your radio / model (wavelength of more than 3 km). If you reduce the meshing, does it resolve your problems? I was able to mesh with standard mesh (and even increase the growth rate on the Advanced tab) and solve the problem and the results looked reasonable.
None of these models are what I would consider high shielding examples - usually all sides would be PEC or high conductivity with very small holes or slots. For your models there are large openings to let fields in. I'm not sure what type of shielding you are expecting (or what shielding level you need to ensure). I thought your model would have PEC on all 6 faces, but the front face would have holes / slots and covered by plastic, but this is not what your models seem to be.
The models seem to model a solid plastic with some faces set to PEC. Is that what you intended to model? I would expect air / free space inside with electronic components (don't model these, I'm just stating what I expect).
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actually this for study purpose,My objective want to proof which material (1.PEC-metal 2.Plastic 3.Combination-metal/plastic) is better for shielding effectiveness . the model is not exactly accurate. So what the suitable frequency for the radio car shielding analysis? (from my understanding radio broadcast frequency is 88Mhz to 108Mhz).
what is high shielding example?
so i assume that the model front side(control button) is plastic(fix), the housing will be metal, metal/plastic & plastic (variable material). i do not take consider the small hole or slot because i want to simple the model.
so you can see the model i attach to you is
1st the front side(control button) ,side left and right is plastic but the back, up and down is metal
2nd model all plastic and
3rd is front is metal only the front side(control button) is plastic
' I would expect air / free space inside with electronic components' do you means Region properties (region medium)
actually yes. i want inside to be free space no material. maybe i confused with lot of model going around.
Could you share your design setup model for better understanding.
maybe you also can share knowledge about shielding or attach journal/ebook or website regarding shielding knowhow?
You can email to me norazlan.ramli89@gmail.com
i really really appreciated your help.
thank you so very very very very much jif.
Kind Regards
A
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I don't have time to create model for you now, but have a look at some of the following links:
- https://insider.altairhyperworks.com/shielding-effectiveness-finite-conductivity-metallic-sphere/
- https://insider.altairhyperworks.com/shielding-effectiveness-metallic-enclosure/
- https://altairhyperworks.com/ResourceLibrary.aspx?keywords=shielding
- How to increase the 'dynamic range' of shielding problems: https://community.altair.com/community?id=community_question&sys_id=74b680ba1b2bd0908017dc61ec4bcb37
- Analysis of the Shielding Effectiveness of a Metallic Enclosure video:
I'll try to reply again later, but possibly only next week.
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thanks jif. really appreciated
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