Learning Forum

[hyunjun]

Hi, I am trying to check interference between antennas using various simulation methods.

In terms of various simulation methods, specifically, one is that both of two antennas are surrounded by PML at once and the other is that each antenna is surrounded by separate FE-BI. TX Port Impedance is antenna input impedance and only RX Port Impedance is conjugate matching to input impedance. In detail, I attached picture and project file.

But, S21 Result of each simulation shows big difference as I already mentioned in title. So, I use Friis Equation to verify which simulation is incorrect. (Beside boundary condition, other terms of setup are same)

Consequentially, S21 of PML simulation is identical to S21 of Friis Equation, but S21 of FE-BI is not.

I think that there is no error in terms of simulation setup. But, FE-BI doesn't satisfy Friis-Equation.

So, anyone who know and explain how this situation happens or think that above simulation setup has something wrong?

Any opinion about this trouble would be greatly appreciated in advance.

• Short Dipole (Specific Spec is explained in picture)
• Antenna Position - Tx(-5, -16, 10) Rx(-5, 16, 10)
• Frequency - 40MHz
• Free Space
• In FE-BI Simulation, small rectangle sheet is located in the distance and assigned to IE region because IE Hybrid Region should be arranged.

• S21 (PML) : 0.019729
• S21 (FE-BI) : 0.0004343
• S21(Friis Equation) : 0.0276

[Praneeth]

Please attach snapshots of your model with FE-BI using "upload image" option in the post.
Also please provide more information about the small rectangular sheet that you are adding as IE region. Any reasons why you feel this should be defined explicitly?
All the very best.

[hyunjun]

Thanks for reply :)
I attached "FE-BI simulation project" and "snapshot".
The reason I define the small rectangular sheet ) At least one IE region should be defined in FE-BI simulation. So, I made the small rectangular sheet very far from the two short dipoles not to affect each other's interference.
In details 1) Interesting Frequency : 28 GHz
2) Small rectangular is defined on PEC & IE region.
3) Short Dipole is excited by lumped port.
4) At first, I simulated with the condition that "port impedance" of all the short dipoles is "50". After simulating, I plotted each other's Z parameter at 28GHz and converted re-normalize port impedance into Z-parameter (for TX) or conjugate Z-parameter(for RX). And Verifying S21.
5) S21 result
PML Boundary Case) S21 : 0.032132
FE-BI Boundary Case) S21 : 0.0043835
Friis Equation Result) S21 : 0.0315
Your reply would be greatly appreciated in advance.
King Regards,

[hyunjun]

pmunaga I forgot to tag you

[hyunjun]

Additionally,
If I simulate with half-dipole on the same condition, result of FE-BI is as same as PML.
So, I doubt the problem might be caused by technical issue in respect to short dipole's small scale.