Research Of Multi-beam Antenna Based On Butler Matrix And Digital Beamforming Network

As for traditional single-beam antenna,communication rate and coverage always contradict each other,so a middle option has to be made between these two indexes.Multibeam antenna solve this problem with advantages of wide coverage,high communication rate and it has been widely applied in areas like radar,satellite communication,base station and so on.Compared with one-dimensional scanning,two-dimensional scanning multibeam antenna further enhance the airspace coverage and data communication rate so that it can communicate with more terminals simultaneously and track more targets.Since the low-cost traditional analog beamforming network(such as Butler matrix)is easy to design,in combination with two-dimensional scanning and traditional analog beamforming network,in this thesis,a multibeam antenna is designed based on the two-dimensional Butler matrix.Firstly,this thesis proposes a kind of SIW three-dimensional interconnection with wideband(71~86GHz)and compact structure.Then a two-dimensional 2×2 Butler matrix-based multibeam antenna,which can generate four two-dimensional beams,is designed based on this three-dimensional interconnection.In order to verify the expandability of this multibeam antenna,on the basis of two-dimensional 4×4 Butler matrix,a multibeam antenna is designed in this thesis,which can generate sixteen two-dimensional scanning beams.At last,the above multibeam antenna is optimized and simulated via HFSS software.The test result is in consistent with the simulation result,so it verifies the feasibility of the multibeam antenna structure and design method based on the two-dimensional Butler matrix.However,the traditional analog beamforming network has its inherent faults,which can only generate a few fixed-angle beams in a limited known number.The digital beamforming network vest the multibeam antenna with flexible control of wave velocity ability of beamforming and high beam switching speed,and free the multibeam antenna from the limit of phase shifter,so as to reduce the size greatly and realize nearly continuous beam scanning.Hence this paper designs a multibeam antenna based on digital beamforming network.Firstly,this paper studies digital beamforming network and the theory of direct digital frequency synthesis,and makes a scheme design for the multibeam antenna based on digital beamforming network.Then the corresponding device in this multibeam antenna is simulated and designed.Meanwhile,since the expandability and the strict limited size of this multibeam antenna,this paper studies and designs diversified three-dimensional interconnection structure in order to realize high-density interconnection under limited size.Besides,the signals interfere with each other seriously since there are so many device in this multibeam antenna based on digital beamforming network,so this paper also presents multiple measures to enhance its electromagnetic compatibility.At last the measure result satisfies the expected result and the proposed index after processing and testing.