microwave absorber modeling in HFSS

[J.C.Maxwell]

the pictuer that i attached had an exaggeration for distinguishing. the real distance that i used is 2 mm from PML for front of antenna in 10GHz.


you mean that the distance should be zero and the pml should attach to the structure.?!
can you attach an instance please?

 

[PlanarMetamaterials]

Hi J.C.Maxwell,

What exactly are you trying to do with that setup? The radiation boundary needs to be at least a quarter wavelength from the radiating portions of the antenna in order to computer the radiation patterns properly. When I say the absorber needs to be attached to the antenna, I mean to absorb backwards directed fields. I assume the radiating aperture in this case is facing the positive z direction.

 

[J.C.Maxwell]

i think i misunderstand your word.
in these attached pictures i used a horn antenna for test the PML operation.
i want to use a PML in front of this horn to see how much it could damp the signal. you said that use PML should be lambda/20 away from the radiator. and i did what you said but no change happened.
so please help more .
i want to test PML. i want to damp the signal in front of this horn antenna in 10GHz. i have 27dB for electric field in front of horn, and i want to reduce it to 5dB with PML.

 

[PlanarMetamaterials]

This has nothing to do with your original post. No wonder you are confusing everyone.

hi guys. i want to model an absorber(like AN75) in HFSS to eliminate the back radiation of a cavity back spiral antenna. how can i do this in HFSS.

A PML works a perfect absorber. What you want is an attenuator. If you want to do this from a material perspective, you need to calculate the medium parameters. And, of course, the material needs to be inside the simulation domain, not on the edge or outside of it.

A much better solution would be to insert a waveguide inline attenuator.

 

[J.C.Maxwell]

hi all.
guys i am completely confused about this problem.
let me to explain in another way.
according to attached picture i want to cancel the coupling between balun and planar spiral(in hfss).
i want to place a material around balun to prevent coupling effect on radiating spiral. in experiment we'll use absorber to reach that goal. but now i want to do this in simulation. please help me solve this guys. thank you very much.

 

[PlanarMetamaterials]

Hi J.C.Maxwell,

I'm not sure if an absorber will adequately cancel near-field coupling like that (but I could be wrong). You may have to investigate shielding and opposed to absorbing.

A PML *might* work in this case, I would put one inside your simulation domain with the absorbing face facing the antenna.

Good Luck

 

[J.C.Maxwell]

hi PlanarMetamaterials .
i tried the PML but it didn't work.

 

[PlanarMetamaterials]

How did you set up the PML? A picture would be great. It's possible that your setup was correct - if this is the case I think this would be a good indication that a regular absorber won't work either for the reason mentioned in my previous post.