How to calculate S parameter for Circular polarized source in Floquet port

- October 16, 2024 at 3:26 am
  
  sornakumarrr
  Subscriber
  
  Hello I am learning how to use HFSS and am trying to replicate a metasurface. The metasurface is designed for circular polarization so I am using floquet ports to simulate a unit cell. I turned on TE mode and also TM mode but with 90 degree phase in edit sources so that it would create a circularly polarized mode. Where I am having trouble is how to read the s parameters for the circularly polarized mode? how to combine the S parameters of TE and TM mode? Please give some suggestions
- October 25, 2024 at 7:50 pm
  
  Irina G.
  Ansys Employee
  
  Hi! Note that Edit sources (where one can turn the modes On/Off and assign phases) affects only fields, not S-parameters. In HFSS, the basic modes of Floquet ports are linear based. There is a matrix that can translate 2 linear modes into 2 CP modes (LH and RH). I hope it's possible to google. Using this matrix, it's possible to tranform scattering S-matrix for linear modes into the scattering S-matrix for CP modes. It should be similar to transformation of single ended S-parameters to Diff/Comm modes S-parameters. Diff pair transition is easier to find. Just follow the steps with the correct description of the modes. It's easier to do for just one Floquet port, something like:
  A_rcp= sqrt(1/2)*[ A_TE+ j*A_TM]; A_lcp= sqrt(1/2)*[ A_TE- j*A_TM]
  Good luck with the math; there is no such an option in standard HFSS features. However, Far Field reporting has an option to report linear and CP polarizations, maybe it will be enough for your simulation goals.
- October 26, 2024 at 1:51 am
  
  sornakumarrr
  Subscriber
  
  Thanks for the suggestion