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On 01/09/2022 14:46, Diane BONKOUNGOU wrote:

Hi Brian,
Thanks for your reply, attached is my code. I put the dielectric at 4.8
it's FR4. I started with 4.29, my PCB was made by PCBway company. I remark
that when I increase permittivity the frequency decrease.
I also try to put a thickness to my copper traces, I finally forgot this
Idea.
After I changed the metal trace with the copper having losses. *%CSX =
AddMetal( CSX, 'ifa' );* change this with the second line
*CSX = AddConductingSheet( CSX, 'ifa', 59e6,
70e-6); %* 59 copper conductivity, 70e-6 is the losses
Also, I try to put a layer of copper in the PCB because it is a 4-layer PCB
and it gives me 2.66GHz, otherwise, I have 2.8GHz.
My PCB is 0.8mm thicker, with 4 layers of elements. And yes, you are right,
the mesh size can be a big factor. I spend a lot of time on the mesh part.
I tried using Detect edge but I get errors all the time. I ended up doing
the meshing by hand.
-I also check the simulation box position my PCB is inside, but I am
wondering if the position is good.
Best regards

I tried the file and get 2.8GHz. The S11 plot seems to be upside down. There must be a negative sign somewhere I've missed; the f_res is calculated for min |s11|. If I change it to max|s11| it makes sense. I have to change the dielectric by 1.5 times to get it down to 2.4GHz, which is away out ,so I don't think it's the choice of dielectric constant. Thickness of PCB didn't change it much.

The resonant frequency will go down if the elements are embedded. You have to make a 4 layer stack as you've pointed out. It's probably this causing the error. The PCB antennas I have are double sided PCB yagis .



Brian