Phased Array Antennas Based On Wide-Angle Matching Layers

Phased array antenna has been widely used in radar technology.In order to enable phased array radar can achieve search,detection,tracking and other functions in a wider space,the antenna with wide Angle scanning performance has gradually become a research hotspot.Because of the active VSWR of phased array antenna might be worse in large scan angle.In this thesis,taking the dipole,tightly-coupled dipole and tightlycoupled double-polarized dipole as examples,the effect of loading wide Angle matching layer on array scanning performance is studied.The contents of this thesis can be divided into the following parts:In the first chapter,the development history of phased array antenna is reviewed,and the development status of wide-angle phased array at home and abroad is introduced from the perspectives of wide-beam element,reconfigurable technology,tight coupling and wide-angle matching layer.In the second chapter,the basic theory of antenna array is introduced,and the effect of mutual coupling in array is discussed.At the same time,the Floquet mode analysis method is introduced.And the performance of a finite array can be determined accurately utilizing infinite array result.In the third chapter,an infinite dipole array which can solve the scanning impedance analytically is taken as the research object.And the influence of metal floor and wide angle matching layer are given.By loading dielectric plate,metal patch or mixed structure above the patch dipole respectively,the scanning performance of infinite dipole array is optimized.However,the above three matching layers mainly improve the scanning performance of D-,H-plane.In the fourth chapter,a tightly coupled dipole with overlapping ends is designed,and the microwave network theory is used to help design a wide Angle matching layer for antennas.Based on the cross structure,the metasurface is designed and its equivalent electromagnetic parameters are derived.The metasurface structure was loaded on top of the antenna,and the scanning performance of the antenna in E,D and H plane was analyzed.By loading the wide-angle matching layer,the active VSWR in each scanning surface of the antenna was optimized with different degrees.In the fifth chapter,a tightly-coupled double-polarization dipole array is designed,and RFSS is placed below the antenna to eliminate the influence by the ground and expand the antenna bandwidth.Then,monolayer,bilayer anisotropy and uniaxial anisotropy materials were added above the antenna.The parameters,thickness and position of the matching layer were optimized in Matlab.The results of the Matlab and HFSS are very consistent.Simulation results of this two software all showed that the antenna scanning performance can be improved by the matching layer loading.but Matlab has higher design efficiency.