Research On Millimeter-wave Beam Scanning Antennas For Terminal Devices

With the development of science and technology,the rapid increase of mobile communication data and the continuous emergence of various new services and scenarios,5G has become the focus of research by domestic and foreign experts and scholars.In the millimeter-wave band,due to the abundant frequency band resources,larger bandwidth and lower latency can be achieved,which can meet the needs of large channel capacity and low-latency transmission in 5G communication.Therefore,the operating frequency of wireless communication has been gradually extended to the millimeter wave frequency band.But there is also relatively large path loss,which greatly reduces the transmission distance.Therefore,there are stricter requirements for the design of millimeter wave antennas.And in order to meet the condition of suppressing the grating lobes,the element spacing is generally set to 0.5λ₀ or even smaller,so it is necessary to add decoupling structures to the antenna array to reduce the mutual coupling between the array elements.In this paper,for terminal devices,the research on millimeter-wave dual-polarized wideband and dual-band beam-scanning array antennas is carried out,and the decoupling technology of millimeter-wave broadband array antennas is also investigated,as follows:1.A millimeter-wave±45°dual-polarized wideband magnetoelectric dipole antenna element and linear array are proposed.The antenna element consists of crossed electric dipoles,the shorting holes as shorting patches,and the Y-shaped feeding structures,achieving an impedance bandwidth of 55.2%（24.4-43 GHz）and stable radiation under two resonant modes.The 1×4 antenna array achieves±54°and±29°beam scanning capability at 26 GHz and 35GHz,respectively.2.A millimeter-wave±45°dual-polarized dual-band dual-ring antenna element and linear array are presented.Based on the design principle of achieving broadband and miniaturization by patch antenna with L-shaped probe feeding and thick dielectric substrate,the antenna element is composed of stacked square dual-ring patches in different sizes and L-shaped feeding probes to achieve miniaturization and dual wideband.And adding parasitic elements improves the isolation of the antenna element at high band.The size of the antenna element is 2.5 mm×2.5 mm×1.16 mm,and the impedance bandwidth is 23%（24.22-30.5 GHz）at low band and20%（36.82-45 GHz）at high frequency,covering the frequency bands of n257～n261.At 27and 39 GHz,the 1×4 antenna array achieves scanning ranges of±58°and±32°,respectively.Finally,in order to facilitate the processing and measuring in practice,some modifications and adjustments are made to the antenna structure.3.A millimeter-wave broadband stacked patches linear array antenna with decoupling surface based on periodic square ring structure is proposed.Firstly,a stacked patches antenna element working at 24.17-29.77 GHz（20.7%）is designed.Then the periodic square ring structure that partially reflects electromagnetic waves is suggested as array-antenna decoupling surface,and loaded into the binary stacked patches antenna array.The results show that the port isolation is reduced by 38.3 d B at 28.5 GHz and impedance matching of antenna is also improved.It was then applied to a 1×6 antenna array,which achieves greater than 15 d B isolation and±60°scanning.Finally,to suppress the backward radiation of aperture-coupled feeding,the feeding structure of the antenna element is also improved by using substrate integrated coaxial line.