Dear @m.dezyani and @mostafanaseri
Thanks for uploading the paper.
I spent quite a lot of time today modifying many things, but I think I could finally obtain the results that we were looking for.
After going over paper, material fitting seems to be identical to as what we have in simulation file. The problem, however, seemed to be due to size of the mesh.
While we were using fine mesh, it looks like it was not quite fine enough to resolve disks and the gap. Thus I modified override mesh, and used conformal variant 2. This significantly improved the results:
A few more things if you wanted to even optimize the results is to perform convergence testing. Particularly, you can use even finer mesh, increase PML layers, and use multifrequency injection.
Please go ahead with practicing them, and let me know if you had further questions,
rp_225_standardPML_largerFDTD_ver2.fsp (1.1 MB)
I hope this answered your question.