Bistatic RCS of RIS

弛 张

Hi all

I built a RIS with 0 ° incidence and 45 ° exit. I need to get his bistatic RCS file. However, when I did the calculations in FEKO, the results I got were different from the theoretical results. As can be seen from Figure 1, there is a strong RCS at 0°, which is far from the theory. Is there anything I need to set up specifically for the bistatic RCS that calculates RIS in FEKO?

Evan_Urban

Greetings,

As long as your Farfield request does not have "Calculates fields in plane wave incident direction" checked you are computing the bistatic RCS in Feko. I would say in POSTFEKO, make sure in the Results Pallette you have your proper quantity you want to analyze checked (For example the specific polarization of the receiving antenna).

Other than that, it is difficult to say what could be the issue with your model without having the model itself. Are you able to share your file and expected theoretical results?

Respectfully,

Evan Urban

弛 张

It's an honor to hear from you，

I also did its bistatic RCS at HFSS and its results were in line with the theoretical values.The results obtained by HFSS, as well as the FEKO model, are attached to the article.

Also, I'm guessing there might be a problem with my media settings. I would like to ask if it is possible to set up the media in a layered way in FEKO.

Evan_Urban

Yes, you have some options for layered dielectrics. You can define a 2D layered dielectric where you define the thickness and the material by selecting this definition. Also, you can go into planes and arrays and choose a multilayered infinite substrate that can include multiple dielectrics and thickness definitions.

I am looking into the model now, it is taking some time to do simulations but I will get back to you once they are complete.

Respectfully,

Evan Urban

弛 张

Thank you very much for your reply and help，

I tried using an infinitely large substrate and the simulation got the right results.

But there is a other problem, the infinite size of the substrate seems to only be built on the XOY plane, yet I need a XOZ plane data import winprop to simulate the wall. There doesn't seem to be a way to change the pitch angle of imported RCS in winprop. Can the 2D layered media you mentioned solve this problem and make the model XOZ surface and get the correct results?

Respectfully,

Zhang Chi

Evan_Urban

弛 张 said:

Thank you very much for your reply and help，

I tried using an infinitely large substrate and the simulation got the right results.

But there is a other problem, the infinite size of the substrate seems to only be built on the XOY plane, yet I need a XOZ plane data import winprop to simulate the wall. There doesn't seem to be a way to change the pitch angle of imported RCS in winprop. Can the 2D layered media you mentioned solve this problem and make the model XOZ surface and get the correct results?

Respectfully,

Zhang Chi

Glad to hear you were able to get identical results after creating a multilayered substrate. I believe you should be able to adjust the orientation of the imported RCS in Winprop. Please give me some time to investigate.

The 2D layered media may provide a solution for this problem, however it appears as though the infinite dielectric was the factor that allowed you to receive the same results as HFSS. 2D layered dielectric uses a face of the model and uses a defined thickness. It may not be necessary in the case of your problem.

Respectfully,

Evan Urban

弛 张

Thank you for your reply,

I've tried this in winprop before, but it doesn't seem to work. You can see that in winprop you can only modify the position of the center as well as the azimuth.

This is the angle relationship between winprop and feko in the Altair manual, but it doesn't seem to have anything to do with pitch angles.

Thank you again for your help

Respectfully,

Zhang Chi

Evan_Urban

弛 张 said:

Thank you for your reply,

I've tried this in winprop before, but it doesn't seem to work. You can see that in winprop you can only modify the position of the center as well as the azimuth.

This is the angle relationship between winprop and feko in the Altair manual, but it doesn't seem to have anything to do with pitch angles.

Thank you again for your help

Respectfully,

Zhang Chi

It appears as though the elevation angle offset is not yet introduced into Winprop, only the azimuthal offset. I believe modifying the model in Feko is the best approach. So, if you desire the RCS pattern oriented in the XZ plane using the planar multilayer substrate may not be ideal. Can you share with me the Feko model where you obtained identical results to that of HFSS?

Respectfully,
Evan Urban

弛 张

Absolutely, I'll append a model that uses layered media to the text.

I've also tried the finite tiering media setup method, and as you all turned out to be incorrect.

Respectfully,

Zhang Chi

Evan_Urban

弛 张 said:

Absolutely, I'll append a model that uses layered media to the text.

I've also tried the finite tiering media setup method, and as you all turned out to be incorrect.

Respectfully,

Zhang Chi

I noticed the Farfield results from the file you provided does not appear identical to the HFSS results you had also posted. Are the Feko RCS results acceptable to you?

Respectfully,
Evan Urban

弛 张

I have compared the simulation results of HFSS with FEKO (with infinite layered media) and their results are not very different and I think they are acceptable. 

The problem now is to get an RCS on the XOZ side, and unfortunately I still haven't found a way to rotate the media.

Respectfully,

Zhang Chi

Evan_Urban

弛 张 said:

I have compared the simulation results of HFSS with FEKO (with infinite layered media) and their results are not very different and I think they are acceptable. 

The problem now is to get an RCS on the XOZ side, and unfortunately I still haven't found a way to rotate the media.

Respectfully,

Zhang Chi

That sounds good, I am continuing to come up with a solution for you to get the pattern in XZ plane and will update you. (Apologize for delay, I was on holiday)

Respectfully,
Evan Urban

Evan_Urban

Hello Zhang,

Apologize for the delay, there was a site maintenance and for some reason it was not allowing me to reply to your post.

I have tested out multiple methods for trying to obtain similar results, however it appears the infinite substrate is necessary for the accurate results.

What you may be able to do is modify the RCS results by exporting the data and using Compose or so to manipulate the data to be in the coordinates you prefer. I can provide some help if you desire it.

Respectfully,

Evan Urban