Rigorous Analytical Model for Multipole Emission Enhancement Using Acoustic Metamaterials

We present a rigorous analytical model for understanding the multipole emission enhancement of sound using acoustic metamaterials. A two-dimensional cylindrical hyperlens-like structure is utilized as a demonstration structure. An analytical expression for the enhanced efficiency is obtained via radiation impedance theory. The analytical results show that enhanced multipole radiation can be achieved by using only one monopole source encircled by the structure. The good agreement between the analytical and the simulation results and the experimental results verifies the applicability of our analytical model. Consequently, our analytical model provides an efficient and intuitive tool for synthesis and analysis of enhanced emission systems.