Research And Application Of Robust And Accurate Pattern Synthesis Algorithm For Smart Antenna

Two pattern synthesis algorithms are studied in this thesis,regarding fast on-orbit autonomous reconstruction with robustness and off-line accurate pattern control respectively.An automatic experimental environment for smart antenna transceiver system is constructed with the design of the related control and testing softwares on PC.The testing and verification of the proposed algorithms are performed on a smart antenna experimental system with 42 element antennas under triangular grid arrangement.The main contributions are as follows:(1)The weak robustness of the existing least mean square alternating projection(LMS＿AP)algorithm in shaped pattern synthesis for large-scale regular arrays are analyzed.It is found that the condition number of the manifold matrix increases sharply with the increase of array size,.leading to the worse numerical stability.In addition,the number of main singular values increases fiercely with the increase of the main lobe beam width of the antenna pattern,making the algorithm more difficult to approach the desired pattern.Therefore,the norm of the weight coefficient vector is introduced as a regularization function to the improved algorithm.Accordingly,the diagonally loaded LMS＿AP representation is derived.Then,a minimum mean square alternating projection algorithm under dynamic diagonal loading is subsequently proposed to dynamically update the diagonal loading factor according to the array size and beam width.The proposed algorithm can greatly improve robustness of pattern synthesis under different array sizes and various beam shapes.(2)Considering the poor sidelobe control ability and low iterative efficiency of existing weight vector orthogonal decomposition algorithms(weight vector orthogonal decomposition,WORD),an improved WORD algorithm based on beam width constraint is proposed for off-line accurate pattern control.The sidelobe control ability is significantly improved by limiting the distance between the angle where the pattern gain needs to be adjusted and the reference angle greater than half of the beamwidth between first nulls.Meanwhile,the iterative efficiency of the algorithm is improved and the number of iterations is reduced.(3)In order to verify the performance of the 42-element transceiver smart antenna system,an experimental system is constructed based on far-field microwave anechoic chamber.Meanwhile,the general control test software of transceiver smart antenna is designed.Then,the basic function and performance of the experimental system are tested,including the pattern synthesis algorithms proposed in this thesis.The work in this thesis lays a solid foundation for the practical application of related techniques in LEO satellite communication system.