Research On Fast And Robust Pattern Synthesis And Anti-jamming Technology Of Smart Antennas

This paper focuses on the smart antenna related techniques for the low earth orbit satellite communication system.A robust pattern synthesis algorithm suitable for on-orbit dynamic reconstruction and an adaptive beamforming algorithm with robust main-lobe and sidelobe control characteristics are proposed.A smart antenna test environment in microwave anechoic chamber is constructed,and the verifications of the proposed algorithms is carried out on the 19-element triangular grid array smart antenna system.First,the existing least mean square alternating projection(LMS?AP)pattern synthesis algorithm is unrobust for the arbitrary-shape pattern synthesis with medium and large scale.It is found that the condition number of the manifold matrix increases sharply with the increase of the array size,especially considering the array mutual coupling.The norm of the weight coefficient vector is introduced into the LMS?AP algorithm as a regularization function.The optimization problem is then converted to a diagonal loading based LMS?AP algorithm.The optimized formula of the improved diagonal loading robust algorithm is derived in detail with the analysis of the stability improvement for the algorithm.The selection of diagonal loading values is given.The proposed algorithm is robust for arbitrary pattern synthesis,and especially suitable for online calculation in large-scale arrays with mutual coupling.Finally,the stability of the proposed algorithm is verified by simulations according to the "iso-flux" gain requirements in LEO satellite communication.Next,to deal with the problems of the existing main-lobe maintaining adaptive algorithm without side lobe control and the sidelobe control adaptive algorithm without main-lobe maintenance,a subspace based linear constraint minimum variance(LCMV)algorithm is proposed.Subspace technique is employed to construct constraint conditions,and the adaptive interference suppression is realized in sidelobe area under the premise of arbitrary shaped main-lobe pattern maintenance and peak sidelobe level control.Two methods are involved to slove the the proposed algorithm.In the first method,the problem is transformed into a second-order cone programming problem and solved by the interior point method.While,in the second one,the problem is converted into an LCMV optimization problem under the quadratic inequality norm constraint of the weight coefficient vector,and a closed-form solution of the optimization problem is given.The derivation of the existence of the closed-form solutions and the high-effective realization structure of generalized sidelobe canceller is obtained,respectively.In the end,the main-lobe maintenance,sidelobe control and adaptive anti-jamming performance of the proposed algorithm,and the robustness of the algorithm under strong mutual coupling are verified by the numerical simulations.Finally,a 19-element triangular grid array smart antenna test system was established.A smart antenna demonstration system setup and display application software is designed.The performance of the proposed algorithms in this paper are all verified in this system.