Research On Design Technology Of Wideband And Multi-mode Orbital Angular Momentum Antenna

Orbital angular momentum antenna is a new type of communication equipment using vortex electromagnetic wave.It has many advantages,such as wide application range,high security and being able to carry a large amount of information.Orbital angular momentum provides a new development direction for antenna research.In recent years,it has received extensive attention from scholars.Moreover,with the development of communication technology,higher demands of broadband and miniaturization is remarkable.In order to meet these needs,combining the characteristics of orbital angular momentum antenna and broadband antenna,wideband orbital angular momentum antenna can be realised.According to its development,this dissertation introduces its principle,design specification,analysis and optimization methods in detail,and summarizes the key technology.In addition,the multi-mode characteristics of orbital angular momentum antenna are one of its important advantages compared with general antennas,which is of great significance for improving channel capacity.Studying the multi-mode technology of orbital angular momentum is of great significance for guiding the design of multi-mode orbital angular momentum antenna.For multi-mode orbital angular momentum antenna,according to the latest research results of many scholars,this dissertation puts forward the design and optimization of highly integrated planar multi-mode angular momentum antenna,which has guiding significance for the design of multi-mode orbital angular momentum antenna,and is convenient for subsequent scholars to expand and reference.The major achievements of this dissertation include the following five aspects:1.Based on the analysis of the traditional design method of the back-fed orbital angular momentum antenna,the wideband orbital angular momentum antennas are designed by using the technology of the stable phase bandwidth of them.Under the guidance of this technique,rotating array elements can be used to generate the phase conditions that satisfy the orbital angular momentum of special modes.On this basis,three broadband antenna elements and three wideband power division networks are designed.They are combined into three wideband orbital momentum antenna arrays,and their performances are simulated and measured.2.By theoretical analysis and software simulation,the feed network based on integrated chip is designed.It contributes theoretical guidance to the design of broadband feed network,facilitates scholars to further study broadband feed network based on theory,and reduces the design complexity of broadband orbital angular momentum antenna.3.An orbital angular momentum antenna based on Butler matrix is proposed,and the phase difference between adjacent output ports generated by Butler matrix with 8 ports is deduced by theoretical calculation,so that antenna elements can be excited to generate orbital angular momentum with different modes.The designed antenna has high integration and low profile,which is convenient to expand on the basis of the antenna structure,and provides reference for the design of orbital angular momentum antenna with more modes.4.A slot-coupled orbital angular momentum antenna with rotatable array element is proposed.Each array element of the antenna can be rotated,so it can generate different spatial phase differences.Combined with slot-coupled feeding excitation,it can generate orbital angular momentum of various modes.The antenna has simple structure and simple design process.On this basis,more modes of orbital angular momentum antennas can be further designed.5.For the proposed antenna,Bayesian algorithm is used to optimize the design,and two parallel optimization algorithms are proposed,which integrate the minimum lower confidence bound and the improved parallel adding point criterion respectively.By using the optimization algorithm proposed in this dissertation,the general performance and modal purity of the antenna can be optimized respectively,which provides convenience for the design of orbital angular momentum antenna.