Generating Mutiple Beams At Dual-frequency From Shared Aperture Meta-surface Antenna

With the progress and development of the times,microwave remote sensing,satellite navigation and wireless communication and other fields of technology updates and iterations,antenna as one of the key components of wireless systems,people’s requirements for its electrical performance index also become higher and higher.The increasingly urgent demand for high-speed data transmission and the shrinking size of wireless devices have made the multi-functional,miniaturized and highly integrated antennas a major research hotspot.The common aperture design method can make the antenna achieve a variety of different electromagnetic radiation performance in the same aperture area,thus enriching the antenna function.The multi-beam radiation approach allows the antenna to access multiple terminals at the same time,thus improving communication efficiency.The meta-surface is a two-dimensional planar array composed of a series of micro-cells arranged according to a certain pattern,which can flexibly regulate the amplitude,phase,polarization state and radiation direction of electromagnetic waves,and has the advantage of being thin and light.Therefore,the study of dual-frequency co-aperture multi-beam antenna based on meta-surface has important theoretical significance and application prospects.The main research content of this paper is as follows.:1.The principle of the meta-surface regulation of the wave-front form,radiation direction and polarization state of the electromagnetic wave is introduced,and the meta-surface electromagnetic model is constructed.The full-wave simulation shows that the meta-surface can effectively regulate the electromagnetic wave.2.A dual-frequency meta-surface with shared aperture is proposed,which can generate orthogonally polarized multiple OAM vortex beams at two frequencies respectively at Ku band.The co-linearly polarized（LP）waves from the source can directly penetrate the meta-surface lens to form multiple OAM vortex beams at one frequency.On the other hand,the meta-surface lens will be capable of releasing the cross-LP counterparts at another frequency with high-efficient polarization conversions to have multiple OAM vortex radiations with different radiating directions and vortex modes.Our design,using laminated meta-surface lens to synthesize multiple OAM vortex beams with orthogonal polarizations at different frequencies,should pave the way for building up more advanced vortex beam communication system with expanded diversity on the basis of the meta-device.3.The meta-surface which can maintain high efficiency polarization conversion in the wide band is proposed,and it is combined with the dual-frequency shared aperture meta-surface to form a folded antenna.The co-linearly polarized（co-LP）waves reflected by the inner surface of the meta-lens would be twisted into the cross-LP counterparts by the meta-mirror and then penetrate the meta-lens to form the high-purity cross-LP directive multiple beams at one frequency.Meanwhile,the other polarization orthogonal meta-array over the outer surface of the meta-lens would also be capable of transforming the released cross-LP fields back and create the co-LP multiple beams at another frequency.As a result,the orthogonal polarization of multi-beam radiation is achieved at two frequencies while the profile height of the antenna system is reduced by two-thirds,and the S₁ of the generated beams are above0.96.Finally,the dual-frequency folded antenna with shared aperture is processed and tested,which proves the radiation function of the antenna.