IE3D Merging Polygons change Simulation Result

Hi, I'm new here, and I would like to ask Dr. Jian some questions regarding IE3D.

I am trying to simulate a Uniplanar Wideband Quasi Yagi Antenna that uses Microstrip to CPW transition into a dipole. However, I noticed that when I change merge the polygons together, I get significantly different results. Is there something I'm not doing right when defining ports and meshing alignment?

I have attached the file. Thanks in advance. I appreciate your help.

Hi, Authur568:

It should be due to the meshing density is not large enough or meshing may not be fully aligned. Meshing alignment is very important for finite dielectrics modeling. Also, we did not take into account of the Er of the finite substrate in estimating the waveguide wavelength. The Er of the finite substrate is 10.2 and it is large for antennas. You may want to increase the meshing density at least by a factor of 2. I am checking the results here and I will get back to you later.

Best regards,

Hi Dr Jian,

Thanks for the response. I have tried to Align Polygon and Dielectric Groups in the alignment setting. The meshing seems to look more uniform. Please let me know how many cells/freq you think I should use to simulate the structure. With the machine I'm using, it's already pretty slow at 35 cells/freq.

Thanks a lot!

Hi, Arthur:

Yes. The finite substrate is relatively large. It may take quite RAM to solve it as finite substrate. The convergence is much slower for finite substrate modeling. Please do try to increase the meshing density to see whether you can improve the convergence. You can also send e-mail to me for further discussion. Regards.