Research On Tri-polarized Antenna Array Beam Steering Technology

In the complicated battlefield background,exploiting the polarization information of electromagnetic wave can significantly improve the performance of radar systems.Array antenna is widely used in air surveillance,precision-guided,missile defense and other fields for its beam direction and shape can be electrically steered to adapt to different battlefield environment.In recent years,with the integration of polarization and antenna array,polarized array is already a leading subject of international radar technologies,and will have broad application prospects.Dual-polarized antenna array suffers scanning gain heavily dependent on the polarization state and polarization degradation when scanning apart from the normal direction,which will severely restrict the effect of generating arbitrary polarization and the performance of two-dimensional wide-angle scanning.The inherent deficiencies of antenna element are the root cause of these problems.Tri-polarized antenna is multi-polarized antenna with a higher degree of freedom,which can achieve spatial diversity and polarization domain,and have received good results in the application of wireless communications,adaptive filtering and other domains.Aiming at improving the polarization array scanning performance,the spatial distribution of the radiation field of tri-polarized antenna element,planar array / conformal array beam steering and characterization analysis,the matched main lobe gain of dual-polarized beam method.The results will be used in target detection,target classification and anti-jamming applications.The main work and research results are as follows:1)Establised the theoretical model of tri-polarized antenna elment,the weights of generating arbitrary polarization are derived.We studied the spatial distribution characteristics of the combined electric field of tri-polarized antenna.It found that the gain of tri-polarized antenna are not sensitive to the polarization state and the polarization purity increased significantly.Furthermore,through theoretical derivation,we proved that when using the infinite current element model,tri-polarized antenna can achieve constant gain hemisphere coverage with arbitrary polarization.Analyzing the performance of the dual-and tri-polarized antenna,and proved tri-polarized antenna unit is the upper limit of the performance of dual-polarized antenna.2)Fuchs optimization methods can not be directly translated into a convex problem,which will increase the complexity of the solution process and can not guarantee global optimization.We proposed a convex optimization based on polarization transformation.In this method,we establish the convex problem by transform the H and V polarization to co-polarization and cross-polarization and then solving the global optimal solution can be obtained by numerical methods.For polarization reconfigurable arrays,we proposed a beam control algorithm which combined genetic algorithm and convex optimization algorithms.By using convex optimization method for each individual to optimize its synthesis beam,the convergence rate improved.Compared with the genetic algorithm,the efficiency of the algorithm is improved.With the above algorithm as a tool to analyze the scanning performance of polarized plane array.We proved that tri-polarized antenna can effectively expand the planar array scanning range.Within the airspace 60°deviate from the antenna plane normal direction,the maximum gain of tri-polarized array is maintained constant,while the main lobe of the cross-polarization level remains at-45 d B or less,while the dual polarization plane array in the same scanning range,there will be the greatest loss within 6d B of gain,while the relative polarization array of three cross-polarization level will significantly deteriorate(rise above 20 d B);3)Established tri-polarized cone array,cylindrical array and other arrays,proved tri-polarized conformal array can achieve separation unit pattern from array factor,which leads to power and polarization can be controlled independently for tri-polarized conformal array.This method is important for generating a main lobe gain matching dual polarized beams.For the control of the array factor of conformal array,a method based on convex optimization algorithm is proposed,by controlling the amplitude and phase of the coefficients,the algorithm can joint optimize the gain,main lobe width and side-lobe level.Algorithm is also suitable for the control of array factor of plane array.4)Dual-polarized beam with independent control suffers mismatch problem.A method based on convex optimization method is proposed for matched dual-polarized beam synthesis.The algorithm enhance the convergence rate compared with invasive weed optimization,while due to the problems is established as a convex problem,the global optimality can be achieved.When applied to a cylindrical array,tri-polarized can significantly improve the level of H polarization at the wide-angle scanning direction,the peak sidelobe level is reduced 5d B or more,while the beam polarization purity has also been significantly improved.