Abstract:In the high frequency standing wave field, the nonlinear superposition of the incident wave and the reflected wave will produce the acoustic radiation force, which can realize the suspension of small objects. Using amplitude modulation or frequency modulation to change the suspension position has space limitation, and the transport stability is poor. In the sound field formed by transducer array, the proposed phase modulation can realize fixed-point focusing and smooth object transportation. Based on the principle of ultrasonic standing wave suspension, the sound pressure and phase distribution of single standing wave, plane standing wave and space standing wave sound field has been analysed in detail. Based on the principle of focusing, phase modulation was used to realize the fixed point focusing of sound field, polystyrene ball suspension and transportation. The results show that the single standing wave acoustic field can be transported stably by bidirectional phase modulation. PLL multi-clock signal can be used to realize multi-direction and different speed simultaneous transportation when the lateral phase difference is π. The sound pressure of the standing wave field in the space array was increased by 83% by fixed-point focusing, and the linear transport of the ball was realized by changing the focal position continuously.