Learning Forum

[Guilin Sun]

It is due to mesh change and possibly the dipole location on the mesh changes.

When symmstry BCs are used, it forces the meshing to be symmetric. The other aspect is, the location of the dipole on the Yee mesh can affect the result. It is better to locate the dipole on the polarization component place:

Please check the meshs. 

If you force the mesh to be symmetric:

Then using symmetry BCs will lead to the same result. Please try, and check the location of the dipole relative to the Yee mesh.