Using WCS-FDTD Method to Study the Plasma Frequency Selective Surface

The plasma is very useful to design the dynamically tunable Frequency Selective Surface (FSS) because of its tunable property. But it is difficult to simulate the plasma FSS by using the conventional finite-difference time-domain (FDTD) method, because the FSS often has fine structure which confines the time step size. To solve this problem, the weakly conditionally stable finite-difference time-domain (WCS-FDTD) method is developed in this paper. The WCS-FDTD method uses auxiliary difference equation to represent plasma's dispersive characteristic, and removes the confinement of FSS's fine structure on time step size by using hybrid implicit-explicit (HIE) technique. So, compared with the FDTD method, the presented method can save a large number of computational time, which are validated by numerical examples. Also, by using the proposed method, the tunability of plasma FSS are validated and analyzed numerically.