聲子晶體(PC)是由兩種材料(背景材料以及填充材料)組成的結構，填充材料週期性地排列於背景材料中。由於結構中材料分布的週期性，使得聲子晶體具有許多特別的波傳現象，諸如能隙、負折射、自我準直等。本研究使用線聚焦PVDF壓電換能器配合V(f,z)方法，量測含有聲子晶體結構的薄板，其結果顯示原本連續的色散曲線在某些頻段出現了不連續斷階，此即因波無法通過結構而產生的能隙現象。未來將利用此量測系統觀察更多聲子晶體的波傳特性。
Phononic crystal (PC) is a kind of structure, which is made of two materials (inclusions and matrix), the inclusions are periodically embedded into the matrix material. The periodicity of the material arrangement leads to some interesting phenomenon of wave propagation, such as band gap, negative refraction, self-collimation and so on. In this study, we use the linefocusing PVDF transducer and V(f,z) method to measure the thin slab with phononic crystals.It can be seen in the results that discontinuity appears at some frequency ranges of the dispersion curves, which means the waves cannot pass through the structure, and is so-calledband gap phenomenon. We will use this measuring system to further investigate more properties of phononic crystals.