Research On The Synthesis Of Large Thinned Arrays And The Design Of Shared Aperture Antenna Arrays

Large array antennas are widely concerned because of their advantages of high radiation gain,high angle resolution and agile beam steering capability.However,the large number of array elements brings difficulties with high design complexity and high manufacturing cost,which also becomes an important factor restricting the development of large array antennas.Array thinning is an effective method to reduce system complexity and cost.A thinned array can achieve the same angle resolution as a full array of the same size,while with a smaller number of elements.Large array thinning is a high dimensional nonlinear optimization problem,and efficient synthesis method has been a hotspot in research area.On the other hand,with the development of wireless communication technology,integration and multi-function become the trend of antenna system development.The shared-aperture antenna design is effective to improve system integration and multi-function.In this paper,a systematic research on the synthesis and design of large thinned array antennas and shared-aperture array antennas is carried out.1.Probability-model based array thinning algorithm design.The characteristics of Fast Fourier transforms in the calculation of array factors and element excitation in thinned linear arrays with uniform amplitude are studied.By analyzing the thinned arrays and the thinning process,a probability estimation model is constructed,which represents the distribution of thinned array.By combining with the iterative Fourier technique(IFT),a thinned array synthesis algorithm based on adaptive probability model optimization is proposed,namely the PLIFT(Probability Learning Iterative Fourier Technique)algorithm.By learning the iterative optimization process through the probability model,PLIFT forms a new optimization and update mechanism,which effectively conques the problem of IFT algorithm that easily to fall into local convergence.What's more,the algorithm maintains high operation efficiency,which proves effective in large array thinning.Then,the PLIFT algorithm is extended to the synthesis of large planar thinned arrays.By adopting the strategy of gradual thinning,the convergence effect of large planar array thinning is improved.In addition,by modifying the objective function of PLIFT algorithm,the synthesis of low-sidelobe sparse array with nulls placement is achieved effectively.2.Synthesis of shared-aperture interleaved array based on mutual exclusion probability model.A mutual exclusion probability model is proposed,which is used to describe the full interleaved array in a common aperture.In fact,the shared-aperture interleaved array could be divided into two independent thinned arrays.Thus,on the basis of PLIFT algorithm,a new algorithm,named EPLIFT,is proposed based on the mutual exclusion probability model for the synthesis of shared-aperture interleaved array.The advantages of adopting the EPLIFT is addressed that: by making use of the transformation relation of a pair of mutual exclusion probability models,the EPLIFT algorithm realizes collaborative optimization of the interleaved arrays in the commom aperture.The two interleaved thinned arrays obtained by EPLIFT have good consistency in mainlobe width and sidelobe performances,and EPLIFT is applicable to the synthesis of both linear and planar shared-aperture arrays.3.Design of shared-aperture array antennas.Firstly,a dual broadband sharedaperture antenna is designed based on the fractal nested structure,and a large array with periodic surface is obtained due to this aperture-sharing arragement.This array achieves the integration of the C-band and X-band antennas in the same plane,so the shared-aperture array has extremely low profile.Secondly,the radiator-sharing approarch is adopted to enhance the scanning angle of a metamaterial-based array.Since the antenna element has periodic structure,the spacing between adjacent elements is not limited by the element size by adopting radiator-sharing approarch.Thus,the scanning capability can be greatly improved,and this design provides a new way of designing wide-scanning arrays by using metasurface-based antennas.Then,the PLIFT algorithm is further employed to design low-SLL array based on the radiator-shared array structure,and low-sidelobe patterns and good scanning performances are obtined with less feedings being included in the thinned array,and the efficiency of PLIFT is also verified by this design.