Research On Suppression Method Of Grating Lobe Of Phased Array

Ultrasonic phased array technology is developed on the basis of phased array radar technology.Its principle is that the electronic system excites each array element according to certain rules and time sequence to flexibly control the position and direction of the focus.However,the presence of beam side lobes and grating lobes in the focused sound field will affect the application performance of the phased array system,such as the presence of imaging artifacts in the ultrasonic phased array detection system or the heat accumulation outside the lesion tissue of the high-intensity focused ultrasound treatment system.As a unequal-distance array,the sparse array can effectively improve the radiation characteristics of the phased array sound field and suppress side lobes and grating lobes.This dissertation first studies the optimal layout methods of one-dimensional linear arrays and two-dimensional concave spherical arrays.Aiming at the one-dimensional linear array,considering the characteristics of the main lobe and side lobe of the sound beam,a full-array sparse method based on the binary particle swarm algorithm is proposed.The full-focus imaging simulation verifies that the optimized sparse array reduces imaging artifacts and improves imaging Effectiveness of efficiency.For the two-dimensional concave spherical array,a set of array parameters with better focusing effect is determined,and the side lobes of the focal plane are suppressed by adjusting the circumferential distance using the constrained particle swarm algorithm.The simulation shows that the optimized array deviates from the array method.It has extremely low sidelobe level when focusing to a certain range of the axis.At the same time,the simulation also shows that the high phase quantization accuracy can effectively reduce the level of side lobes and grating lobes,and increase the focal energy.Furthermore,according to the different application scenarios of the phased array,based on the principle of direct digital synthesis(DDS),two12-bit phase shift control precision multi-channel drive circuit design schemes are given,including the amplifier circuit and the upper computer design scheme.Among them,the use of the clock buffer makes the single-chip microcomputer and DDS chip solution in the technical realization of each additional electronic channel only consumes one GPIO,which can be used for array drive occasions with a large number of elements,FPGA and digital-to-analog conversion(DAC)modules The solution can be used for arbitrary wave phase control,short-period pulses and other array drive situations that require flexible control of excitation waveforms.Finally,according to the proposed hardware design scheme,the corresponding array drive circuit is made.The waveform test and focus experiment of the board verify the validity and feasibility of the drive circuit design scheme.