A Research Of Millimeter Wave Orbital Angular Momentum Reflectarray Antenna

With the development of science and technology,the communication channel is becoming more and more crowded.Using the orbital angular momentum of electromagnetic wave to enlarge communication channel can be seen as a new potential method.Moreover,the reflectarray antenna can be used to generate the orbital angular momentum(OAM)electromagnetic wave effectively because the phase of the reflectarray can be deigned arbitrarily.In this paper,the theoretical analysis and experimental methods are used to research and analyze the design of OAM reflectarray antenna,and the thesis includes the following four parts:I.Analysis of high gain OAM reflectarray antenna:(1)The physical characteristics of OAM electromagnetic wave are studied.Also,the physical characteristics of OAM electromagnetic wave and the external manifestation of OAM electromagnetic wave are analyzed.Based on the theoretical analysis and the design method of the reflectarray antenna,the phase distribution of the OAM reflectarray antenna is researched.Combined with the design method of the reflectarray antenna,the phase distribution of the OAM reflectarray is studied,and the main influence of the antenna parameters on the OAM electromagnetic wave is analyzed.(2)The design method of high efficiency folded OAM reflectarray is studied.The problem of high profile and low efficiency of the conventional space fed OAM antenna is improved by using the topology of the folded reflectarray.In order to realize this topology,a kind of antenna element with high-efficiency and high-polarization-isolation is proposed in this paper.The element can solve the problem of achieving wide phase coverage and good polarization isolation at the same time due to the multi-resonant structure and the connection structure are used.After reasonable designing,the new element can be used to maintain high polarization isolation and the wide phase coverage at the same time.By using the new antenna element,the OAM antenna designed in this paper can maintain high-gain,high-efficiency,high OAM mode purity and excellent performance in a simple process and smaller volume.(3)The design method of four modes half aperture-reuse OAM reflectarray is studied.How to generate multiple modes of OAM electromagnetic wave is the key problem of OAM multiplexing communication.In order to achieve this goal,this paper presents a half aperture-reuse OAM antenna topology.In this structure,different OAM modes are generated by four different rectangular aperture(four rectangular aperture is overlapped with each other).Furthermore,this paper provides a theoretical analysis on the OAM mode and orthogonality of the OAM electromagnetic wave with elliptical aperture.Finally,the test results show that the four mode half aperture-reuse OAM reflectarray can produce four kinds of elliptical OAM electromagnetic wave.The isolation between different modes is greater than 20 dB.II.Research and design of broadband high gain OAM array antenna:(1)Research and design of broadband large aperture reflector antenna.The design method can enable the antenna array to track phase change of frequency,so that the entire array in the wide band to maintain good phase compensation.In order to verify this method,a single aperture large aperture reflector antenna with a diameter of 32.48?28GHz is designed and fabricated.The peak gain of the antenna is 36.1dBi,and the 1.5dB bandwidth is 26GHz-33.3GHz(24.6%).Compared with the same aperture reflector antenna,the antenna can increase the bandwidth of 7% to 24.6%,which has high application value.(2)The design method of broadband OAM array antenna is studied.Because the traditional OAM antenna is based on the point frequency design,when the frequency of the antenna changes,the mode purity of the OAM electromagnetic wave will deteriorate seriously.In order to solve this problem,the method of element resonant point insertion is used to design the array.The reflectarray antenna designed by this method can track the phase compensation in the whole frequency band,so as to maintain good phase compensation in the frequency band.In this paper,a broadband OAM reflectarray antenna is designed.The broadband OAM array antenna designed by this method can maintain a good OAM mode purity in the 28GHz-34 GHz band.