Guilin Sun
Ansys Employee

From the image and result, it seems the mode source is not well supported by this waveguide, as its intensity decreases sharply with propagation distance.

 

Could you please check the mode source and make sure the mode fields are not truncated by PML and the mode source is large enough.

In addition, you do not need to reinstegrate the Poynting vector as the power-monitor can directly give you accurate transmission.

 

You may also enable "frequency dependent profile" and have 10 to 20 frequency points to overcome the problem of frequency-depedent mode profiles.