Microstructure of composite materials can have a profound effect upon the performance of microelectronics composed of those composite materials. Conventional analysis based on quasi-homogeneous models neglecting the structural details of the composites is inadequate. Micromechanical analysis is more complex but can provide a more realistic treatment. We have investigated the propagation of a signal in a periodic composite to examine the essential of a micromechanical analysis. By analyzing the state of the composite material just before and after the wave front as well as on both sides right next to the interfaces, we have determined the strength of the propagating signal. The results show that the property differential between material components is critical in determining the energy dissipation. In composite materials made of dissipative components such as polymers,structural details of the composite materials contribute further to the energy dissipation.