Feko Help - calculate shielding effectivness

[waseem44]

Feko Help

Someone please help me I have recently started using feko I modelled a enclosure and wat t calculate shielding effectivness my problem is i change the thickness but cannot see difference in shielding effectveness smeone plz help me how thicknessare provided in feko i am giving the thiknss in face properties thickness option
someone please help me as early as possible

 

[mvr]

Feko Help

What levels of shielding do you expect? If you have a "fully enclosed" enclosure (i.e. no holes) then the MoM can only give you about 40 dB of shielding. This is a fomulation based restriction - remember, you are discretising the currents so it can not give you infinite shielding.

If you make the thickness several skin depths deep you won't be able to model that with any MoM code.

 

[waseem44]

Re: Feko Help

Thanks very much dear

so what does it mean should i model a real enclosure (having seam/holes) . i will be able to see the thickness effect, then?
i have seen in literature shielding results quoted above 60dB shielding and thickness effects, using feko.If u know some web address it will be helpful for me also
waiting for your response

 

[mvr]

Re: Feko Help

I doubt if the literature model was a fully enclosed one. Perhaps one with holes? If you have holes, then using the Surface Equivalence Principle you can model the inside of the enclosure with an air dielectric (eps_r=1). This will give you "dynamic range" up to about 80 dB.

 

[waseem44]

Re: Feko Help

Thanks

Are you saying that even an enclosure with apertures cannot give results more than 80dB in Feko wheras it is practically possible to achieve more than that.
I have read feko gives errors in shielding factor at oblique incidence only and for other cases it gives good results matched with analytical and experimental .
waiting for reply

 

[mvr]

Re: Feko Help

The 80dB is my personal experience. Maybe I made some modelling mistake, dunno. As for the oblique incidence thing, I wouldn't believe everything I read
But seriously, I wouldn't believe a statement that just says:"FEKO does not work for oblique incidence". It depends on the model, the excitation type, and many other factors. Maybe it was user error, who knows.

 

[waseem44]

Re: Feko Help

thanks
I didnt mean to say that fekoe does not work for oblique incidence, but some literature says it differs to some extent wih empirical results for larger oblique incidence
My problem of thickness effects on shielding still remains there. Today i modelled an enclosure with a slot but sill unable to see thickness effect. Then I used my Flo emc software it gives very pronounce effects as thickness is changed (but i want to se feko). If u think i am making some mistake can u provide me ur modelled feko file where i can see results on different thickness.
thanks for help
waiting for reply

 

[mvr]

Feko Help

post your file here then we can have a look

 

[waseem44]

Re: Feko Help

Dear
Thanks for ur help. Finally I succeded to see thickness effect in SE.

 

[waseem44]

Re: Feko Help

I need some suggestions on feko, people plz share their experiences
I have modeled a cylinder of aliminium with upper lid of different thicknesses
i have followin problems

1- when i change thickness from .5 to 2 and 3mm cannot see much diference for 3mm at 10KHz how i can improve it ?
2- secondly i modeled 2mm solid lid by defining a dielectric with aluminium properties as in feko solid conductors cannot be defioned
i gave a seam by giving a gap of .05mm on upper lid
2ndly does all softwares need some seam to be introduced or only MOM based

waseem

 

[livalivatem66]

Re: Feko Help

I am bigginer at FEKO software and i want to measure the shielding effect of a hollow cube with a hole in the face opposite to the source.
I created the cube, but i don't know how to measure the shielding effect
I am gratefull to anyone can help me with my problem
Best regards

 

[rrfekousr1]

Re: Feko Help

Dear
Thanks for ur help. Finally I succeded to see thickness effect in SE.

Hello, I am facing the same limitation on how to get FEKO to simulate the thickness effect on shielding effectiveness for an enclosure. I read you were able to succeed on simulating the thickness impact. could you please share what you did? Thank you.

 

[sim4me]

There's a nice page in the Help Centre on that. Hope you have a login and browse to "How to increase the "dynamic range" of shielding problems in FEKO".

 

[enkaar01]

Re: Feko Help

I am bigginer at FEKO software and i want to measure the shielding effect of a hollow cube with a hole in the face opposite to the source.
I created the cube, but i don't know how to measure the shielding effect
I am gratefull to anyone can help me with my problem
Best regards

u can do it by defining near field starting frm unshielded portion to shielded, and then see the result of near field inside and outside. this is SE