Research Of Broadband Multi-beam Antenna Based On Butler Matrix Network

The 5G mobile communication network is gradually expanding its commercial use.Its base station antennas will co-exist with the existing 2G/3G/4G systems(at least 4G systems)for a long period of time.The contradiction between the lack of site resources and the increasing capacity is increasingly acute.To increase system capacity,2G/3G/4G base station antennas are split into dual-beam applications;5G uses large-scale array antenna applications alone.In order to increase the system capacity and integrate multiple systems into one antenna under the premise of considering the complexity of the system and cost practicality,the UWB dual-beam antenna has become the first choice for application.According to this application prospect,this dissertation chooses a dual-beam base station antenna that can cover2G/3G/4G/5G multi-system and have a ultra-wide band(1695MHz-2690MHz)as a research topic to adapt to the needs of large-capacity co-construction and sharing,and solve the problem of lack of site resources caused by the separation of the antenna system and the establishment of sites.In response to the above requirements,this dissertation intends to study the directional coupler under the UWB problem,and the dual-beam Butler matrix feed network designed by this extension,and the dual-beam base station antenna will be implemented by this network,the specific contents include:First,in order to break through and expand the bandwidth of the Butler matrix feed network,this article creatively designs a wide-band three-branch directional coupler based on microstrip line,which output signal has a better amplitude and phase flatness compared to the traditional four-branch and five-branch directional couplers,thereby obtaining wider frequency band characteristics.Further,the straight-through port and the coupling port of the broadband 3-d B bridge(directional coupler)are connected in stages with an unequal 180°directional coupler to obtain a broadband 2 × 4 Butler matrix network.Compared with the traditional 2 × 4 Butler matrix network,the matrix network structure in this dissertation eliminates the cross junction and Wilkinson power divider,which is beneficial to the broadbandization and integration of the circuit.Next,this dissertation studys and designs the dual-wave beam base station antenna with the working frequency band of 1695MHz-2690MHz(applicable to the 2G,3G,4G and 5G frequency bands).The content includes: 1)Research and analysis of the array form of the dual-beam base station antenna array: Through the theoretical calculation and simulationcomparison,the array parameters of the horizontal and vertical planes are determined,thereby forming a 4×10 scale antenna array,and further optimizing the array form to obtain better radiation performance;2)Preferably the above-mentioned broadband 2 × 4 Butler matrix network,the network can make the antenna radiate two sub-beams directed on demand in the horizontal plane;3)To achieve the verticality of the dual-beam base station antenna planar beam forming,a one-tenth power division network is designed to achieve the preset down-tilt angle of the antenna vertical plane pattern,while maintaining a low side-lobe level.Finally,physical tests have been carried out on UWB dual-beam antennas,and the measured results of antenna agree with the simulation results,which meet the design requirements,and thus the stereotyped products were put into practical engineering application.