Research On Quasi-Planar Substrate-Integrated Two-Dimensional Scanning Multibeam Array Antenna

In recent years,the mobile communication technology has rapidly developed and the traditional communication technology has been unable to completely fulfill the requirements of emerging applications.Especially the fifth-generation mobile communication possesses the characteristics of higher transmission rate,larger bandwidth capacity and lower delay.To improve the capacity and spectrum utilization,Massive multiple-input multiple-output(Massive MIMO)as an essential technology plays the important role in the construction of the fifth-generation mobile communication system.Among them,two-dimensional scanning multibeam array antenna as one of significant carriers in the field of Massive MIMO,its application in the fifth generation of mobile communications has attracted widespread attention from academia and industry.This dissertation will study the miniaturized and planar two-dimensional scanning multibeam array antenna based on the current problems such as complex structure,large volume,and difficult integration.In addition,this dissertation will study the high-gain and lowsidelobe two-dimensional scanning multibeam array antenna in order to tackle the key issues such as low gain,high sidelobe,etc.With the aforementioned targets,the main contents and main contributions of this dissertion are listed as follows.1.Research on miniaturized and quasi-planar 2-D scanning multibeam array antenna: Starting from 1-D scanning multibeam array,this dissertation analyzes the essential reason why feeding networks suffer from a relatively large size,and studies operation principles of two types of feeding networks,i.e.,circuit-type and lens-type.Related to Butler matrix and Cassegrain lens,two different methods of miniaturized designs are proposed.For Butler matrices,a stack-up method is presented,based on which an E-plane Butler matrix is developed.Compared with traditional H-plane Butler matrices,the size of the E-plance Bulter matrix is reduced by about 75%.For Cassegrain lens,a folded configuration is proposed and developed into a miaturized Cassegrain lens design with a size of 11.6?×7.4?.On the basic of 1-D scan,this dissertation further explores the difficulty of compact 2-D scanning multibeam array antennas.As a solution to the connection between sub-networks,a new topology to combine E-and H-plane subnetworks is proposed.Regarding the connection between feeding network and radiation portion,a ladder-type array is developed.What's more,this dissertation pays attention to reducing the size of the sub-network,which can further improve the compactness of the final design.2.Research on low-sidelobe 2-D scanning multibeam array antenna: Starting from 1-D scanning multibeam array antenna,this dissertation theoretically analyzes the key factors affecting sidelobe levels.By analyzing the amplitude and phase,this dissertation tries to find out an effective method to manipulate the sidelobe level.This part also includes two types of feeding networks and devotes to suppressing the sidelobe level of Butler matrices and Rotman lenses.For Butler matrices,a dual-layer topology is proposed,which can greatly reduce the path overlap and increase the compactness.Compared with traditional designs,the footprint of the Butler matrix is reduced by about 50%.For Rotman lenses,a dual-port excitation method is proposed to increase the edge taper at the array plane,thus reduce the sidelobe level.Using this method,the maximum sidelobe level is reduced from ?11d B to ?18d B.On the basic of 1-D scans,this dissertation explores the new method to suppress the sidelobe level of 2-D scanning multibeam array antenna.Firstly,a new topology providing tapered amplitude in two directions is proposed.After that,a quasi-planar low sidelobe level 2-D scanning multibeam array antenna is developed in substrate integrated waveguide techonolgy.This design has reduced sidelobe level in E-plane(H-plane)from-12 d B(-8d B)to-19 d B.3.Research on planar 2-D feeding network: This dissertation analyzes the main reason why traditional 2-D feeding network has trouble in planar design and then explore the possibility to transfer the 3-D topology into 2-D case.Starting from the topology of 2-D Butler matrices,a new planar configuration for feeding network design is proposed.The key is to take the basic components of the 2-D Butler matrix apart and rearrange them in a planar configuration.This dissertation theoretically demonstrates the feasibility of planar 2-D feeding network design.To further simplify the feeding network,a modified topology is proposed to reduce the amount of path overlap by introducing several eightport crossovers.By doing so,the complexity of the whole network is greatly reduced and it becomes easier to design such a planar 2-D feeding network.After that,this dissertation focus on the planar component designs.Firstly,the topology of eight-port coupler is transferred from 3-D to 2-D.Later on,an eight-port crossover is designed by using dualport excitations.Then 2-D phase shifters are designed based on the new topology.Combining these basic components,a planar substrate-integrated 2-D feeding network is finally realized.4.Research on high-gain 2-D scanning multibeam array antenna: This dissertation analyzes the key factor affecting the gain of 2-D scanning multibeam array antenna.To overcome the limitation of scaling up traditional 2-D scan,a new method is proposed here.Such a method can successfully separates the beam forming into two parts,i.e.,1-D feeding network and pattern-reconfigurable antenna.Based on this new topology,a new type of feeding network,i.e.,horn lens is proposed.This lens can conveniently increases the output ports and feed a larger array.After that,a modified horn lens is developed by introducing new phase-compensation method to reduce scanning gain loss from 3.9d B to 2.2d B.In the meantime,a new phase shifter is designed to increase the phase shifting range.For the pattern-reconfigurable antenna,a fixed-frequency leaky-wave antenna is designed using substrate integrated waveguide technology,whose radiation angle can be manipulated by the pattern of binary unit.By combining these two parts,a high-gain 2-D scanning multibeam array antenna is finally designed.