Figure 5.

Dispersion curves of the periodic structure in figure 4 when (a) Ω = 100 rad s⁻¹, (b) Ω = 500 rad s⁻¹, (c) Ω = 1060.14 rad s⁻¹ = Ω* and (d) Ω = 1500 rad s⁻¹. The length of the periodic cell is L = 6 m. The dashed lines in (a)–(d) represent the case Ω = 0. We note that the scales of the vertical axes in (a) and (b) are different from those in (c) and (d).