The notation immediately followed by the port indicates port number and the notation after dots indicates the corresponding mode. Accordingly S11 is reflection coefficient and S21 is the transmission coefficient.

Thank you for your input sir but still i am not identifible which one is S11 and which one is S21 in S parameter of Floquet port dB(S(FloquetPort1:1,FloquetPort1:1)), dB(S(FloquetPort1:1,FloquetPort1:2)), dB(S(FloquetPort1:1,FloquetPort2:1)), dB(S(FloquetPort1:1,FloquetPort2:2)), dB(S(FloquetPort1:2,FloquetPort1:1)).etc Krunal Patel

If port 1 is excited then S11 is the first option. S21 is not there in the options specified by you.

I suggest you reduce the number of Floquet modes to 2. Then you will get a simpler matrix of 4 parameters, similar to11, 12, 21, 22. Which software are you using?

Krunal Patel

dB(S(FloquetPort2:1,FloquetPort2:1)), dB(S(FloquetPort2:1,FloquetPort2:1))

Is it what you are saying?

The main role in definition has the 1st number in name of the port. As an example:

S(FloquetPort1:2,FloquetPort1:2) = S11,

S(FloquetPort2:2,FloquetPort1:2) = S21,

S(FloquetPort1:2,FloquetPort2:2) = S12.

Anveshkumar Nella , it is still reflection coefficient.

Yes, I agree with Krunal Patel :

S(FloquetPort2:1,FloquetPort2:1) = S22

Thanks for your inputs. It is very good to have them.

One more final query is that how many modes are usually preferred for floquet port excitation?

What are the modes we define?

thank you Vadym Slyusar sir for your clear understandable inputs

Thank you sir Krunal Patel for valuable suggestions

and thank you sir Anveshkumar Nella for following the question and raising the clear issue with the concern

thank you Abhirupa Saha madam for your suggestion, but i am using only two ports in HFSS

Hello Mr. Raeen..

At the time of excitation of floquet port you have selected 2 modes, in which one is TM(0,0) plane wave and another one is TE(0,0) plane wave. Let assume TE(0,0) is the first mode, So in this result dB(S(FloquetPort1:1,FloquetPort1:1)), shows that the transmitted plane wave is TE(0,0) at port 1 and reflected TE(0,0) at the same port. Similarly dB(S(FloquetPort1:1,FloquetPort1:2)), shows that excited wave at port 1 is TE(0,0) and reflected TM(0,0) wave at port 1. In a similar way other results also you can analyze.

Note: Here the port no. shows from which port you are exciting the wave or receiving the wave and second number is showing the mode.

In my case, 2 floquets ports are used to FSS excitation for both TE and TM modes in the CST studio suite. The reflection and transmission coefficients are points out for both TE and TM modes in the figure below. In this way, other results will be analyzed.