Research On Wide Bandwidth Angular Scanning Technology Of Spherical Conformal Array

Since the concept of phased array antenna was put forward in the 1930 s,the technology of phased array has attracted the attention of many researchers,and has been a research hotspot.Phased array antenna is widely used in civil or military fields.However,it is very difficult to realize wide-angle scanning for both linear and planar arrays in broadband environment.With the increase of scanning angle,the coupling between the elements in the array leads to the rapid deterioration of active voltage standing wave ratio,which is always the difficulty of broadband wide-angle scanning.Since the conformal antenna can conform to the surface of the carrier,the requirement for the spacing of the elements is not as strict as that of the planar array.The expansion of the spacing of the elements will greatly reduce the coupling between the elements in the array.This characteristic becomes a cut-in for wide-bandwidth angular scanning.As a kind of conformal phased array,spherical conformal phased array also has the advantages of conformal array.Compared with ordinary conformal array,spherical conformal phased array has more advantages in large angle scanning.Therefore,the study of spherical conformal phased array has great value.Aiming at the wide-bandwidth angular scanning of spherical conformal phased array,this paper studies the design of broadband elements suitable for spherical array and the scanning of spherical array.The main research contents and work summary are composed of the following three parts:In the first chapter,the development of conformal antenna and the research status and methods of conformal antenna by experts and scholars are described.In the second chapter,the basic theoretical knowledge of the antenna is mainly described,and based on the synthesis of any antenna array pattern,the theoretical formula of the spherical array pattern synthesis is derived.In the third chapter,based on the microstrip antenna,a wideband microstrip slotcoupled antenna is designed.The antenna works between 7.11 GHz and 12.89 GHz with a relative bandwidth of 57.8%.We also research the effect of parameter changes on the antenna.At high frequencies,the antenna's back radiation is larger because of the influence of feeder radiation.In order to improve the pattern change caused by the radiation of the feeder,a back grounding plate is added behind the feeder.The feeder structure is changed from microstrip transmission line structure to stripline-like structure.The TE and TM modes in the stripline structure are suppressed by adding short-circuit screw between the upper and lower grounding plates.After the structure improvement,not only the bandwidth of the antenna is increased,but also the influence of feeder on the antenna pattern is eliminated.The final operating frequency of the antenna is between 5.72 GHz and 12.52 GHz,and the relative bandwidth is 74.5%.In the fourth chapter,several common arrays of spherical conformal phased array antenna are introduced.The disadvantages and disadvantages of these arrays are also analyzed.The method of equal latitude distribution is proposed to improve the arrays,and a 5-layer spherical conformal array with equal dimension distribution is designed.In the process of spherical array scanning,aiming at the problem of beam depression in 0-degree scanning,the causes and solutions of beam depression are put forward.Then,the coupling between the units in the spherical conformal phased array is analyzed.At the same time,the active voltage standing wave ratio of the spherical array are discussed during the scanning process.Finally,the reason for the increasing scanning gain for the spherical array scanning is discussed.Analytical explanations were made.When the spherical array is scanned between 0 and 90 degrees,the gain variation is within 4.56 dB,and the scanning performance is good.