Research On Multi-beam Sharpening Technology Of Uniform Circular Array Antenna

The beam sharpening method of uniform circular array antenna in ADS-B receiver is studied in this paper.Due to the special geometry of the circular array,its beams have similar directivity in any direction in space.However,compared with other types of arrays,in the case of the same array element,the beam width of the circular array antenna is wider and the side lobe level is higher,which greatly affects ADS-B receiver operating efficiency.The composition of the 1090 ES data link ADS-B system is introduced firstly in this paper,including the transmitting subsystem and the receiving subsystem.At the same time,the structure of the ADS-B signal of the 1090 ES data link is introduced.A mathematical model of the ADS-B signal is proposed and relevant simulation experiments are performed.Based on this model,the correlation between the ADS-B signals is studied.Secondly,in view of the problems of the beam of the uniform circular array being wide and the sidelobe level being high,the effects of the number of array elements and the radius of the array on the pattern of the uniform circular array are studied.At the same time,the principle of phase mode excitation is introduced,and simulation experiments are performed.Experiments show that after phase mode excitation processing,the received data of the circular array can be transformed into a structure with uniform linear array characteristics.Thirdly,based on the virtual linear array formed by phase mode excitation,two beamforming methods based on linear prediction method and particle swarm optimization are proposed.Both methods can effectively expand the array aperture,sharpen the beam width and reduce the sidelobe level,and improve the angular resolution and anti-noise capability of the array.Finally,the beamforming method proposed above was applied to ADS-B deinterleaving.The interleaving probability of the signal on the ground-based ADS-B receiver is studied,the probability of collision of different numbers of ADS-B signals in different situations is analyzed.And then the interleaving signal separation method based on the signal DOA is researched to realize the ADS-B interleaving Signal separation.