Research And Design Of Multi-beam Antenna And Beam-steering Antenna Based On Metasurface

With the rapid development of modern radio communication technology and radar technology,the requirements for antennas are more and more high.antenna with single beam can no longer meet the diverse requirements of modern communication systems.Therefore,multi-beam antennas are more and more widely used.Metasurfaces can adjust the amplitude and phase of electromagnetic waves by controlling units on a sub-wavelength scale,and can obtain unique electromagnetic properties that natural media do not possess.Therefore,it provided new way for the realization of multi-beam antenna.In this thesis,two multi-beam antennas based on the metasurface are researched and designed.The specific work is as follows:（1）A multi-beam antenna based on metasurface is proposed.The overall size of the antenna is 2.3λ₀×2.3λ₀.By employing the metasurface as radiating element above the feed suorce,steering the beam in the elevation plane is realized.Furthermore,the substrate placing above the metasurface helps to reduce beam width.Meanwhile,each beam has a radiation zero pointing atθ=0,thereby avoiding the overlap problem of the pattern.The results indicate that the working frequency of the antenna is 5.82 GHz.When the four input ports are excited separately,the antenna generates four beams pointing to different directions.The maximum radiation directions of the four beams are（φ,θ）=（0°,32°）,（90°,32°）,（180°,32°）,（270°,32°）,the gain of each beam can reach 9.3 d Bi.Moreover,by adjusting the feed source,beam is steered in azimuth plane.When the length of the left patch decrease from 11.95 mm to 10.45 mm,the azimuth angle of four beams can be adjustable between 0°～22°,90°～112°,180°～202°,270°～292°,respectively.（2）A miniaturized beam-steering antenna base on metasurface and multi-stub microstrip line is proposed.By loading the patch units on the lower half of the dielectric substrate,a metasurface with discontinuous phase distribution is formed.Then,it is placed above the feed source and the beam is deflected on the elevation plane.Also,the beam width is reduced through adding the stub.The results indicate that the four beams are pointed at（φ,θ）=（0°,27°）,（90°,27°）,（180°,27°）,（270°,27°）.Furthermore,when the feed source microstrip are reduced respectively,the azimuth angle of each beam can scan between-47°～47°.Compared with the antenna proposed in 1),it has smaller size,lower profile and larger beam variation range in azimuth.