近年来，以参量阵为基础的定向声发射技术由于其轻薄的体积优势得到了广泛的关注。虽然许多的研究工作都致力于降低参量阵的失真水平，但是参量阵的指向性控制却未得到很好的发展。目前的相关工作都还局限于单频相控参量阵。这主要有两方面原因：首先是缺乏兼俱低复杂度和高准确性的参量阵模型；其次，对相控参量阵的宽带波束形成算法缺少必要的研究，没有考虑到非线性失真的指向性以及超声信号的空间混叠等复杂因素。本项目拟从构建宽带相控参量阵的指向性模型入手，分析基带信号和失真分量的指向性，研究宽度波束形成算法，分析多波束形成算法在空间混叠条件下的性能，使相控参量阵性能得到多方面升级。本项目的研究将为相控参量阵的推广提供技术积累和理论支持。

With the ever increasing interests in directional sound devices, the parametric array becomes an attractive approach for its small size. However, most of the previous works have been focusing on reducing the nonlinear distortion of the parametric array. There are only a limited number of works addressing the steerable parametric array. This can be due to two reasons. Firstly, a concise yet accurate model to describe the wideband directivity of the steerable parametric array is still missing. Secondly, wideband beamforming algorithms are not readily available for the steerable parametric array, since the directivity of the nonlinear distortion components and the spatial aliasing of the ultrasonic frequencies are complicated to analyze. Therefore, this project proposes to firstly model the directivity of the wideband steerable parametric array. Based on the model, wideband beamforming algorithms can be analytically investigated and improved. Furthermore, multi-beamforming algorithms are examined under complicated spatial aliasing conditions. The aim of this project is to provide the necessary theory and technique to promote the usage of the steerable parametric array.