Guilin Sun
Ansys Employee
Hi´╝îtransmission can be be meaningful when the DFT monitor is in parallel to the source plane for periodic structure with Periodic BCs. The YZ monitor can monitor E fields but not the transmission. In theory, if this YZ monitor is exactly on the periodic BC, it should record zero transmission. In your case XY monitor gives correct transmission only. xz and yz monitors are not for transmission calculation. They are only helpful if you want to know where the fields are strong.
Power equals the integration of Poyinting_vector dot plane_normal , please refer this
The analysis group gives you the power density, not the power except T_total. Only after integration along x,y and z then can you get the power. Since you are using analysis group, please refer this solar example
In general, if you only have interest in transmission/reflection, just use Power DFT monitor, not the analysis group, which is less accurate than the power monitor along, since the analysis group has additional interpolation and integration which could introduce errors.