feko waveguide port

Under plane wave incidence, what is the propre way to extract the transmission/reflection [S matrix] for an arbitrary shaped structure having NO ports [ex. metamaterial structure] in FEKO?

In metamaterial simulation, CST and HFSS are widely used. I don't know people using FEKO to simulate metamaterials. But I think in principle it works too. By NO ports, do you mean you just computed the problem as scattering? Then you got the scattered field, from which you want to obtain conventional S-parameters?

A structure with NO ports is meant to be used WITHOUT a direct excitation connection. For example, in contrary to a horn antenna which is usually excited through a wire feed [direct connection], any dielectric plate material [not necessarily a metamaterial] to be simulated have NO ports since it is simply a dielectric sheet without any connection. Hence, in order to obtain the S matrix [S-parameters] of such a structure, it is necessary to embedd ports in the simulation. Wire ports are not convenient since the results will depend on the location of the placed ports and thus this is a false procedure. One way could be the use of a "waveguide port"?! How this could be done in FEKO?
However a problem remains: a plane wave is the one of concern, but a rectangular waveguide port just supports TE or TM and NOT TEM. Maybe this could be solved by placing simultaneously two waveguide ports one being restricted to TE and the other to TM waves.
Any experience in the field?

i've worked on FEKO but with direct feed on ports, no idea about finding out s parameters without defining ports , but i feel its not feasible , u need to define the ports.
or u can place that structure in waveguide and the define the ports and calculate the sparameters