Abstract: A novel finite-difference freqency-domain method is presented for the analysis of electromagnetic wave propagation in periodic structures. The boundary conditions are set according to Floquet's theorem for periodic structures. Floquet's theorem is used both on the electric field boundary and the magnetic field boundary. Thus, the computational domain is restricted to a single period, and the absorbing boundary conditions can be used on the other boundaries. The propagation constant can be obtained by means of calculating matrix eigenvalues, and there is no need to solve the high-order equation. In this way, the calculation time is greatly saved.

Key words: finite-difference freqency-domain, Floquet's theorem, periodic guided waves structures, matrix eigenvalues