Research On Beam Optimization Design Of Vector Circular Array

In recent years,array signal processing technology has been widely used in radar,wireless communication and other fields.Beamforming is an important subject in array signal processing.It can form the directivity of the receiving system,suppress noise and interference,and estimate the arrival direction of the signal.In the array structure,the research of circular array is more and more important.It can obtain 360°azimuth information without ambiguity,which has a great advantage.By beamforming,target detection and location can be realized.The performance of beamformers can be evaluated from the aspects of robustness,array gain,sidelobe and main lobe width and response,and beam optimization is to optimize these parameters.In this paper,the beamforming technique of acoustic vector circular array is studied from the perspective of modal domain signal processing.In practical scenarios,there are errors in both the steering vector and the noise covariance matrix,which will seriously degrade the performance of the high-gain beamformers.Therefore,a robust beamforming method for circular array in phase mode domain is proposed in this paper.The simulation results show that the system can still achieve better array gain and improve robustness under the influence of array amplitude error and phase error.Sidelobe control is an effective method for sidelobe level optimization.Due to the interference of the undesired direction and the high noise correlation,the sidelobe of the array will rise,so sidelobe control has become an important problem in beam optimization.In this paper,the phase mode domain processing of the zero groove method,which can form a zero in the interference direction of the side lobe region,control the side lobe height in the designated area;At the same time,the lowest sidelobe beamforming of the circular array is also proposed,which is still in the phase mode domain,and is realized by the second order cone tool.Through simulation and experimental data processing,it is verified that this method can effectively reduce the sidelobe of the beam pattern and reduce the false alarm rate compared with the general method.In the aspect of beam main lobe,the design of beam main lobe response can be considered.When fitting the desired beam response,sometimes what we are really interested in is the main lobe region of the beam.If we approach the desired beam in all directions,it is equivalent to adding equality constraints in the side lobe region,which will increase the fitting error between the synthetic beam and the main lobe region of the desired beam.Therefore,this paper proposes a method in the phase mode domain.When the circular array broadband beamforming,only the expected main lobe response is used to fit the main lobe response,which can eliminate the unnecessary side lobe redundancy constraints,make the main lobe approximation accuracy higher,and the main lobe will not change with the frequency.For this method,this paper gives the simulation and experimental data processing,the results verify the feasibility of the algorithm.