相位共轭阵列及其形成的相位共轭声场

相位共轭法可实现声波反向传播和自适应聚焦，用于声源成像。从理论的角度梳理分析基于测量声压使用单极子源（PC/M）、基于测量声压梯度使用偶极子源（PC/D）、基于测量声压和质点速度使用单极子源和偶极子源（PC/P）这3种相位共轭阵列及其形成的相位共轭声场之间的关系，以及PC/P相位共轭声场与源声场的关系。从倏逝波和传播波角度给出上述3种阵列能否突破衍射极限的理论依据，并基于线列阵进行数值仿真，给出阵与源的距离、阵元间距、阵元偏移对各阵聚焦的影响。结果表明：当阵长一定时，在近距离处PC/D聚焦效果最佳；在阵与源距离较远处，以半波长阵元间距的PC/M聚焦效果最佳。

Phase conjugation in underwater acoustics

Phase Conjugate (PC) arrays can make sound waves travel backwards to converge, which can then be used to build the image of a noise source. This paper reviews and analytically studies three types of PC array (monopole PC array (PC/M), dipole PC array (PC/D) and perfect PC array (PC/P)) and the phase-conjugated fields produced by the arrays. The relationship between the sound field produced by the source and the phase-conjugated fields produced by the arrays are discussed. The various PC schemes are compared and analyzed from the evanescent wave component and the propagating wave component. The metrics of the focusing properties of PC arrays and the effects of the array element spacing on the focusing properties are discussed. The spatial resolutions of various PC schemes with different distances between array and source are studied numerically with linear arrays. The element deviation is also discussed. A numerical simulation shows that PC/D with half-wavelength element spacing is effective at near field focusing, and PC/M with half-wavelength element spacing is effective at a greater distance.