Spatial-Temporal Patterns Arising in Active Media Due to the Wave Instability

Wave instability in active media gives rise to formation of different types of spatial-temporal patterns. Here we discuss patterns which may arise in the vicinity of the wave bifurcation. First we consider patterns which arise due to polymodal interaction right after the wave bifurcation and obtain the conditions for them to occur. Then we suggest the scenario of transition from standing waves to travelling waves with the half-wavelength observed in experiments.