microwave absorber modeling in HFSS

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J.C.Maxwell

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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.
in addition AN75 has a reflection curve like attached picture.

thank you in advance

 

Re: eccosorb modelling in HFSS

that should be easy, just set materials u, u', etc. in the HFSS.
No need to get the performance.
 

Re: eccosorb modelling in HFSS

hi tony.
i didn't understand.
i cant see material u or u' in hfss.
you mean i change the materials properties?
if you mean that what is the electrical properties of eccosorb like AN75?
 
Last edited:

hi.
i want to model an absorber in hfss in a specific frequency. (like 10GHz). for attenuate the back lobe of radiation of an antenna.
and i dont know the electrical properties of material like epsilon and mu and loss tangent.
 

J.C.Maxwell said:
hi.
i want to model an absorber in hfss in a specific frequency. (like 10GHz). for attenuate the back lobe of radiation of an antenna.
and i dont know the electrical properties of material like epsilon and mu and loss tangent.
Click to expand...

So what do you need help with in HFSS?
 

Re: eccosorb modelling in HFSS

Why is this a separate thread from this one? And why is this simulation question not in the simulation section of the forum?

J.C.Maxwell said:
whats happen to edaboard?!!!!!
Click to expand...
It has been taken over by people who don't know how to ask questions properly.
 

PlanarMetamaterials said:
So what do you need help with in HFSS?
Click to expand...

i think there is a way in HFSS to attenuate a signal maybe with PML or something else.
my problem is attenuating signal in simulation. maybe with modeling an absorber in HFSS and put in the back of antenna or using a way to attenuate backlobe.
 

Yes, a PML will work as an absorber. So would a radiation boundary, or some other absorbing material. It depends what your specific requirements are. Are you trying to model a real life absorber, or will a PML be sufficient?
 

i just want to attenuate . not a real absorber.
if pml could do this it will be sufficient.
im designing a 2-18GHz spiral antenna with cavity back. i want to attenuate the backlobe in cavity.
how can i use the PML to eliminate the backlobe in cavity.
what is the PML setup for this problem.
 

J.C.Maxwell said:
hi. it didn't work.
Click to expand...
What didn't work?

J.C.Maxwell said:
and the propagaion of wave did not changed with useing PML.
Click to expand...
What do you mean the propagation didn't change? The wave would either be absorbed, in which case the PML is working perfectly, or it is reflected, in which case there is indeed a change.

Tomsin yin said:
what is the u'?
Click to expand...
Permeability. Usually u' is the real part, but in the context it was given i would assume imaginary part.
 

i used PML with default values in five side of a horn antenna. but i didn't see any major change in the propagated signal level in front of antenna. and the pattern have kept its shape and no change happened.
there is some question about PML setup.:
1: how far the pml should be placed away from antenna?
2: for operate as absorber which one should be set for "Base Face Radiation Properties"? "radiation only" or " incident field".
3: how much should be set for "Uniform Layer Thikness"?
4: how much loss should be happened for radiated field with PML?
 

J.C.Maxwell said:
i used PML with default values in five side of a horn antenna. but i didn't see any major change in the propagated signal level in front of antenna. and the pattern have kept its shape and no change happened.
Click to expand...
Do you mean five sides, where you put a PML around every side of the antenna except the aperature? I'm not sure how this would be accomplished, can you show a picture?

J.C.Maxwell said:
1: how far the pml should be placed away from antenna?
Click to expand...
At least 1/20 of a wavelength, the further the better though, depending on what you're trying to do.

J.C.Maxwell said:
2: for operate as absorber which one should be set for "Base Face Radiation Properties"? "radiation only" or " incident field".
Click to expand...
Radiating only.

J.C.Maxwell said:
3: how much should be set for "Uniform Layer Thikness"?
Click to expand...
I usually use about 1/20 of a wavelength.

J.C.Maxwell said:
4: how much loss should be happened for radiated field with PML?
Click to expand...
I'm not sure what you're trying to ask here. The reflection off of the PML should attenuated more than 20 dB of the incident.
 

Hi J.C.Maxwell,

Why are you expecting that these PMLs will affect your radiation pattern? If you want to change the back lobe radiation pattern, your absorber needs to be attached to the antenna.
 

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