Research On Dual-band Multi-polarization Feed And All-metal Reflectarray

As mobile communications moves toward the 5G era,the demand for antenna performance is gradually evolving.Reflectarray antennas with powerful functions such as high gain,multi-beam,and beamforming can meet many potential demands for 5G communications as a low-cost alternative to Massive MIMO or smart antennas.Besides,multi-polarization communication,with unique advantages in channel enhancement,has significant application value in some specific scenarios of5 G communication.In this paper,dual-band multi-polarizaition feed system and all-metal reflectarray for 5G applications are proposed and investigated.The dual operating bands include 28 GHz and 60 GHz,which are both the potential 5G bands.The multi-polarization mode includes two linear polarization,left-hand circular polarization,and right-hand circular polarization.The multi-polarized radiation capability of the reflectarray antenna is obtained by the illumination from the feed system with multi-polarization mode.The feed system consists of two parts,including a dual-band feed antenna and a feed network.The feed antenna adopts a new type of coaxial corrugated horn.By introducing a set of choke slots at the inner wall of the coaxial structure,excellent radiation performance and good dual-band pattern symmetry are obtained on the premise that the dual-band phase centers are substantially coincident.In addition,a feed network with orthomode transducer(OMT)as its core component is designed for the feed antenna,and switchable dual-band multi-polarization excitation is realized.For the first time,a staggered array of crossed rectangular waveguide elements is used to construct an all-metal reflectarray.By adjusting the height and depth of each waveguide element,dual-frequency phase compensation and beam control are achieved.The simulation results show that the proposed reflectarray achieves good pattern performance and nearly 100% radiation efficiency in a total of eight operating modes of dual-band and multi-polarization.The feasibility of the designed reflectarray for dual-frequency multi-polarization radiation and the low loss advantage of the all-metal structure in the millimeter wave band are both verified.