I am trying to simulate a gold resonator on substrate excited by an incident linearly polarized plane wave. I am using the scattered field formulation to do this (instead of port boundary conditions) in order to easily plot the electric field enhancement (electric near field / background electric field).
The goal is to simulate an array of such resonators, and so far I have been using the continuity boundary condition on the sides of the unit cell to model this. However, I don't think this is correct, as I am getting some strange effects at certain frequencies of the incident beam (it sets up what looks like a specific mode of the electric field enhancement within the substrate--not sure how to best describe this).
However, when I try to set up floquet periodicity instead of continuity b.c.s, the k vectors in x,y, and z must be defined. However, I am completely lost as to how to do this. I'm not even sure of the physical significance of continuity b.c.s versus floquet b.c.s.
If someone could explain this difference, and how to set up the k vector definitions, I would much appreciate it!