900MHz Yagi simulation

[mzk]

Hello,

I would like to re-simulate antenna that I've simulated in 4nec2. There I have good SWR.
However in openEMS I do get different impedance.

I changed the mesh several times, played with the boundary conditions (MUR, PML) and also with the elements shape (cylinder vs square). I did notice that the cylinder (wire primitive) didn't work or is much different despite it should be almost the same. Do I have to use cylindrical mesh instead of rectangular?

Attached are the nec file and the octave script.

Any ideas would be helpful.
Thanks!

PS: the zip file contains both the nec and the openems' .m files.

[mzk]

I have some progress! I used cylinder primitive instead of wire and square. Probably the square (not hollow) element is very different.

The simulation with the cylinder achieves almost the same result as the real measurement.

[Hale_812]

there is no difference between primitives. Every object is converted into a set of rectangular boxes. so define the mesh carefully.