Research On Digital Encoding Holographic Antenna For 5G Millimeter Wave Communication

In recent years,5G communication technology has gradually replaced 4G as a research hotspot in mobile communication in the new era due to lower network delay and faster data transmission speed.The main operating frequency bands of 5G include Sub-6GHz and millimeter wave frequency bands,among which communication in the millimeter wave frequency band puts forward higher requirements for radio frequency devices and antenna structures.The key technologies of 5G millimeter wave communication mainly include Massive MIMO,beamforming technology and beam management technology,which require the 5G millimeter wave antenna to have a larger array scale,faster beam switching speed and larger beam scanning range.As a mainstream solution,traditional phased array antennas can cover and meet the above-mentioned communication requirements well.However,large-scale phased array antennas are greatly limited in the millimeter wave frequency band due to the larger transmission loss and more complex processing technology.Therefore,there is an urgent need for a new array antenna with certain beam scanning capability,relatively simple structure and less insertion loss.Under this background,the electronically controlled scanning holographic antenna can achieve a certain accuracy of beam scanning without introducing large insertion loss,making it a worthy research scheme and a new research hotspot.In this paper,the design and verification of electronically controlled scanning holographic antennas used in the millimeter wave band are presented.The main research work is as follows:1.Based on the beamforming theory of holographic antennas,this paper proposes a radial waveguide dipole array holographic antenna.The Amplitude quantization is performed according to the phase distribution of array units,and the threshold judgment is used to screen the reserved array units.The HFSS simulation results show that the proposed structure can accurately realize the broadside radiation and the beam pointing of phi=150,theta=30。In the operating frequency band of 27.5-29.5GHz,the antenna efficiency is greater than 62%,while the beam pointing fluctuation is less than 2,and the pattern gain is greater than 20d B.Compared with the traditional radial waveguide slot array holographic antenna,it has the advantages of smaller beam pointing fluctuation and lower side lobe level in the working frequency band.2.This paper proposes a one-dimensional waveguide slot array holographic antenna fed by SIW.In order to realize the reconfigurability of the unit radiation,the control circuit is designed and verified on the waveguide slot unit,so that the gain change of the unit cell in the working and non-working states reaches 13.8d B,and the effective control and distinction of the unit state are realized.Then,the slot units are arrayed to construct a one-dimensional waveguide slot array holographic antenna model,and the causes of the sidelobe deterioration of the antenna pattern in the case of a one-dimensional narrow waveguide slot array are analyzed,along which solutions.Finally,the above beamforming optimization ideas and schemes are written into a holographic beamforming optimization algorithm,which is used to guide the modeling and simulation in HFSS.The simulation results show that the optimized holographic antenna array has more accurate beam pointing,smaller beam pointing fluctuation band and lower sidelobe levels in the operating band.3.Based on the above one-dimensional array,a 36*16 parallel-plate waveguide slot array holographic antenna is designed in this paper.Firstly,a 1 to 16 power divider based on SIW is designed to excite a plane wave whose main mode is the TEM mode in the parallel-plate waveguide.Based on the two-dimensional slot array,the overall control circuit network is designed.Later,the difference and model equivalence of the parallel plate waveguide in non-E-plane beamforming and E-plane beamforming are analyzed,and the traditional holographic beamforming formula and holographic antenna beamforming optimization algorithm are respectively applied to calculate the switching matrix of the antenna array element.The HFSS simulation results show that the proposed antenna array can achieve beam scanning from 0to 60 in the case of E-plane and non-E-plane.The overall test results of the antenna show that in the operating frequency band of 25.5-27.5GHz and under different scanning angles,S₁₁<-7.5d B,the beam pointing fluctuation is less than 4,and the antenna efficiency is greater than 25%.This paper completes the overall design from fixed-beam holographic antenna to digital encoding holographic antenna.Simulation and test results verify the effectiveness of the principle of holographic beamforming and the feasibility of beam-reconfigurable holographic antenna,laying a certain foundation for the commercial application of digital encoding holographic antennas in the future.