Efficient Analysis And Synthesis Of Large Scale Four-Dimensional Heterogeneous Antenna Arrays

The array antennas have the ability of improving system gain and flexible beam control,which are widely used in various radio systems.The development of modern radio systems is changing rapidly,and the electromagnetic environment is becoming more and more complex.Consequently,the rigorous demands of the performances of arrays are proposed,especially for array antennas on airborne and shipborne platforms.In order to satisfy the application requirements of low sidelobe,high gain,omnidirectional detection,and multifunctional integration,etc.,the array antennas need to be developed toward large-scale arrays,which bring great challenges to the design of the array antennas on platforms.However,the topological structures of traditional array antennas are almost all in the form of planes,and the control of the radiated power is only realized by the control of excited amplitudes and phases.Therefore,it is impractical to directly install large array antennas on the pre-designed and limited space of the carrier platform.Meanwhile,the feeding networks composed of tranditional transimit/receive modules are expensive and complicated,and the degree of freedom provided by the feeding network is not enough to solve some complex array radiation problems.Therefore,it is necessary to expand the radiation aperture and increase the degree of freedom of the array antennas based on their physical nature and the possible forms of new types of array antennas.From the array topology,the positions of elements of a heterogeneous array are determined by the shape of a platform and are arranged on the pre-designed and limited three dimensional space of the platform,which is able to achieve a large effective aperture and omnidirectional detection field of view.On the other hand,an additional degree of freedom of time is introduced to four-dimensional(4-D)antenna arrays,which can be used to improve the ability of array radiation control and simplify or transfer the design difficulty of the feeding network.Therefore,a new type of antenna arrays named 4-D heterogeneous antenna array will be very helpful to solve the new technical challenges in modern radio systems.This dissertation takes the heterogeneous antenna arrays and 4-D antenna arrays as research objects,and focuses on the efficient analysis and synthesis methods of 4-D antenna arrays,especially for the large scale 4-D heterogeneous antenna arrays,and preliminarily study the spatial spectrum estimation based on 4-D antenna arrays for system level application.The main content and innovative achievements of this dissertation are summarized as follows:1.The radiation mechanism of four-dimensional antenna arrays under arbitrary time sequence and array topology are studied from time-and frequency-domain including mutual coupling effect for the first time.In particular,the basic physical architecture of the 4-D antenna arrays is firstly introduced;five unified equations with respect to the power pattern,active reflection coefficient(ARC),input power,reflected power and radiated power of 4-D antennat array in time-and frequency-domain are systematically summarized;the relationship of the main physical quantities between the 4-D antenna array and the static array is clarified;and a novel synthesis method based on DE-AEP-ARC in the presence of mutual coupling effect is proposed.Finally,the radiation mechanism of the four-dimensional antenna array and the effectiveness of the new synthesis method are demonstrated by the simulation and measurement results.2.A method based on partial convexities is proposed for the synthesis of large scale 4-D heterogeneous antenna arrays.In particular,the radiation mechanism of heterogeneous antenna arrays is studied deeply,and the expressions for the calculation of the far-field pattern of a 4-D heterogeneous antenna array are derived according to the coordinate rotation transformation.Based on the analysis of the partial convexity of the optimization problem,two greatly efficient optimization algorithms are proposed(hybrid optimization algorithm and joint optimization algorithm).The former is particularly suitable for the synthesis of small 4-D antenna array,and the latter is particularly suitable for the synthesis of large 4-D antenna arrays.Finally,through numerical simulations and comparative studies,the efficiency of the proposed optimization algorithms and the advantage of improving the directivity by the heterogeneous way are verified.3.A method based on fully convexity is proposed for the efficient synthesis of large 4-D heterogeneous antenna arrays for the first time,in order to avoid using global optimization algorithms and further improving the optimization efficiency and optimization results.Meanwhile,based on the full analysis of the convexity of the optimization problem,the convex optimization algorithm and iterative convex optimization algorithm are respectively proposed for the efficient synthesis of large 4-D heterogeneous antenna arrays.The former achieves a faster optimization speed at the expense of shrinking feasible range,which is suitable for the fast optimization of a large four-dimensional antenna array.The latter is compatible with multiple time modulation ways and is suitable for arbitrary array topology structure.The number of sidebands which can be suppressed is arbitrary,and the polarization pattern can be considered in the optimization algorithms.Finally,the effectiveness of the two algorithms is verified by numerical simulations and crosswise comparisons.4.An iterative convex optimization algorithm based on active element pattern(AEP)and ARC is proposed to efficiently synthesize 4-D heterogeneous antenna arrays.This algorithm not only has the advantages described in the third point above,but also considers the mutual coupling effect between the array elements and the port matching,which is particularly suitable for the synthesis of small-scale or tightly coupled 4-D heterogeneous antenna arrays.Finall,the efficiency of the algorithms and the advantage of improving the gain obainted by the heterogeneous way are verified by numerical simulations and prototype mearsurements.5.A fast synthesis algorithm based on iterative Fourier transform for the synthesis of large non-uniformly spaced 4-D antenna array is proposed.In order to further accelerate the optimization speed and meet the real-time requirement of pattern synthesis in engineering applications,based on the idea of exponential function interpolation,a fast synthesis algorithm for large scale non-uniformly spaced 4-D antenna arrays is proposed.Numerical simulations show that the optimization results are able to meet the design requirements,and the optimization speed is much faster than the reported optimization algorithms in the existing literatures.Finally,to extend this algorithm to synthesize 4-D heterogeneous antenna arrays,the dissertation also shows the study on how to use threedimensional fast Fourier transform(3D-FFT)to calculate the radiation pattern of 4-D heterogeneous arrays.6.A novel spatial spectrum estimation method for 4-D antenna arrays based on optimized time sequences and sparse signal recovery is proposed.In particular,the signal model and sparse signal recovery model using 4-D antenna arrays are firstly established.The mutual coherenc and covariance matrix of noise are then introduced to quantificationally analyze the influence of different time sequences on spatial spectrum estimation,and the spatial spectrum estimation method of 4-D antenna arrays based on optimized time sequences and sparse signal recovery is proposed accordingly.The optimization results show that the unidirectional phase center motion(UPCM)scheme is particularly suitable for spatial spectrum estimation of 4-D antenna arrays.Finally,numerical simulations with respect to spatial spetrucm,probability of resolution and estimation accuracy in different scenarios,crosswise comparisons and pratical measurement are used to verify the the effectiveness of the estimation method.