Spiral Waves in Media with Spatial Period-2 Structure

The spiral waves in a system of two-dimensional coupled oscillators with spatial period-2 structure are investigated. We find a sandwiched spiral wave where any adjacent oscillators are in anti-phase. We show that the propagation rate of the sandwiched spiral wave is insensitive to the change of the coupling constant. The influences of the local kinetics on the sandwiched spiral wave are also investigated.