Problem with simulation in HFSS

[Nikoleta Andreadou]

hfss full book v10

Hello,
I am trying to simulate a Frequency selective surface (dielectric + substrate) with HFSS. The structure is periodic in x and y axis. I want to derive s11 and s21 parameters. I use two virtual boxes (air) above and below the structure. I assign the waveports at the outer surfaces of the boxes (parallel to xy plane). I assign the master and slave boundaries to the surfaces of the boxes that are perpendicular to xy plane to denote periodicity.
The results are not the ones expected. Does anybody have any idea of where my mistake lies? Any kind of help or suggestions are very welcome!

Thanks in advance

 

[asdfaaa]

fss calculator

I dont think you can simulate FSS by assigning waveport, you can try planewave excitation.
Regards,

 

[Nikoleta Andreadou]

hfss fss project

I have also thought of plane wave excitation, but how will I derive the s parameters with such an excitation? In fact, what I want is the reflection and transmission coefficient.

 

[sassyboy]

hfss fullbook

Nikoleta

Firstly, for FSS simulation of S-parameters, the best choice of Ansoft's solutions is the Ansoft Designer. You can carried out a thorough FSS simulation in about 20 minutes (inclusive of project setup time and simulation duration).

If you have only the HFSS in your hand, then this gets a little more exhausting, but it can be done (I am sure you know already, but just HOW?)

asdfaaa is right, you don't use waveguide port. In fact, it is definitely the plane wave source. This is how you would do it in a the laboratory where the FSS under test is placed between a pair of horn antennas are used to lauch and receive a continuous plane wave propagation. Never in one's mind should a waveguide port be employed.

Secondly, mustn't keep thinking about S-parameters. It is actually the power levels you are concern about. There are three power-levels you must modelled. They are Total Radiated Power, Total Reflected Power and Total Transmitted Power for a sweep of frequencies. You need to define three cut planes in your air box corresponding to the three items I just mentioned.

Finally, this is a more advanced task. I only know this in version 8. The Field Calculator is used to integrate E-field on each cut-planes to obtained the corresponding power level. Sadly this is too much of an effort to explain it to you. However, the HFSS technical support will have instructions and tutorials on how this is done. In version 9 and later, I believe the field calculator is no longer available and I think one needs to write a vbscript program to do all of that. A very challenging task!

These are the advice I can offer you in regards to FSS simulation in HFSS. Hope this has shredded some sense to you. As I said in the beginning, depending on the level of experience you have with HFSS, a easy solution would be to use Designer.

Kind regards, Sassyboy

 

[harikrishna]

hfss perfectly matched layer

Hi!Nikoleta Andreadou

The FSS Simulation can be done using the planewave excitation. As far the Field calculator is concerned, its very much available in HFSS ..Ansoft has Field calculator in all the versions.Only thing is to check it out in HFSS>Fields>Calculator if you are using HFSS v9.x

You have more features added in HFSS v10.0 for FSS applications.Check out the website www.ansoft.com

thanks,
Hari
Bangalore,India

Added after 29 seconds:

Hi!Nikoleta Andreadou

The FSS Simulation can be done using the planewave excitation. As far the Field calculator is concerned, its very much available in HFSS ..Ansoft has Field calculator in all the versions.Only thing is to check it out in HFSS>Fields>Calculator if you are using HFSS v9.x

You have more features added in HFSS v10.0 for FSS applications.Check out the website www.ansoft.com

thanks,
Hari Krishna
Bangalore,India

 

[Nikoleta Andreadou]

hfss 10 full book.zip

Thank you for your replies,
I tried to simulate the FSS by using plane wave excitation. I defined two cut planes at a distance λ/4 approximately from the source. One of the cutplanes is above the FSS structure and the other beneath it, in order to calculate the reflection and transmission power level respectively. The radiation boundaries are a bit further from the cut planes defined. I plotted the magnitude of E field on the cut planes, but no useful conclusions can be derived. Do I need to integrate the E field by using the equation E(x,y,z)=∫(j*ω*µ0*Htan)*G+(Etan×G)+(Enormal*G)dS ????
(I found this type in the HFSS help file). Is this really the way to do this?

Any suggestions?

 

[Zottiri Kusuta]

hfss far field excitation

You may need to use PML's (perfectly matched layer) between the air and waveports. A similar exercise is given in HFSS Full Book v10.0

**broken link removed**

See Example 5.7 - Endfire Antenna Array.

I also suggest this 10.0 version of the so called "HFSS Full Book" to other interested HFSS learners since it covers some additional exercises to 9.2 version.

 

[costox]

contionus wave hfss

I have a question, related to this topic because of the two antennas facing each other.
If I have two dipoles (or 1 dipole and 1 loop antenna) facing each other (one sends signal and one receives), what kind of ports should I use on each of them to measure the received power?
Thank you.