Research On Null-notch Beamforming Algorithm For Arc Array Antenna

The arc array antenna can be designed to fit the surface of the carrier platform that runs at high speeds such as aircraft,missiles,and satellites,which can also produce a relatively large antenna effective aperture,obtain a larger observation range and a smaller carrier load and other characteristics.Hence,it has become a research hotspot in the antenna field and an important development direction of phased array radar in the new century.Beamforming technology is the key technology for array antennas to obtain high gain and anti-interference.However,due to the complicated pattern analysis and calculation of arc arrays,multipath coupling effects and the existence of cross-polarization components,the traditional linear array beamforming algorithms can not be directly applied to arc arrays,which brings certain difficulties to the practical application of arc array antennas.The subject focuses on the arc array antenna configuration and its null-notch beamforming algorithm.The main work and innovations of the thesis include the following aspects.1.Aiming at the problem that the traditional linear array algorithm is difficult to directly apply to the arc array,the thesis focuses on the spatial geometric conversion relationship between the arc array and the linear array.Taking the center array element on the arc as the benchmark,the angle between normal of each element and the spatial unit vector is obtained according to the maximum direction of the array beam.Combined with the effective work element selection strategy of the working element,the working element is selected by using the radio frequency matrix switch.Then the phase difference between each working array element and the reference array element on the arc is calculated according to the maximum beam direction of the array.The phase shifter is used to compensate each element,and the equal phase plane perpendicular to the maximum beam direction of the array is generated.The bridge between the arc array and linear array is built,which lays the foundation for the traditional null algorithm applied to the arc array.2.Aiming at the problem of interference suppression failure caused by fast moving interference or data mismatch between antenna array and interference,under the background of array,the existing four null broadening algorithms have been improved.The two angles of single-angle wide null and multi-angle wide null are compared and analyzed.The depth and width of the null formed by the four algorithms at the interference angle away from the main lobe and close to the main lobe are compared and compared to the main lobe and side lobe.Impact,computational complexity,etc.The simulation verifies the effectiveness of the improved algorithm on the arc array.3.In the case of small snapshots and coherent sources,the output signal-to-interferenceto-noise ratio of the Capon beamforming algorithm drops sharply,and the performance of the algorithm is significantly worse.An iterative adaptive nulling beamforming algorithm based on color loading is proposed.This method uses an iterative adaptive method based on the principle of maximum likelihood to perform accurate spatial signal spectrum estimation on a small number of sample signals received by iterative updating,and uses the result of the spatial spectrum estimation to construct the sampling covariance matrix of the signal.The sampling covariance matrix and the prior covariance matrix constructed from the prior information of the interfering signals in the sample use the color loading factor to form the color loading covariance matrix,and finally the minimum variance and distortionless beamformer is used to obtain the best weight to form the null Vector,the rapid convergence of the proposed algorithm and its null depth and widening effect under different interferenceto-noise ratios are verified by simulation.