Millimeter-wave Multibeam Antennas For 5G Mobile Terminals

The unparalleled update and massive deployment of 4G LTE(Long Term Evolutoin)technology signals the start of the global mobile communication stepping into the era of wireless broadband.In spite of this,the explosive growth of wireless traffic puts the mobile network under overload incessantly,which has greatly deteriorated the quality of wireless Internet service.The global research into the next generation of mobile network(5G)has been triggered almost simultaneously since then.Inherent with a wide bandwidth,millimeter-wave will enable some visible improvements in channel capacity and data rate.However,it will experience climbed loss,attenuation and depressed efficiency when travelling through PCB circuits and the atomosphere.These problems remain to be solved,still.In this paper,the research work will centralize on 5G millimeter-wave feeding networks and antennas.Multibeam schemes will be tentatively utilized to enhance the radiation gains and beam coverage as well.The general PCB circuits,such as microstrip circuits,often exhibit rampant dielectric and radiation loss.The millimeter-wave circuits manufactured by these PCBs barely satisfy the certain engineering requirements.Embarrassingly,the traditional close-structured waveguides are difficult to be highly miniaturized and integrated,even though they are inborn with low loss and the capability of anti-interference.Apparently,these two structures are not advantageous in mobile terminal application,which often require low power-consumption and are normally conditioned by the limited size.The substrate integrated waveguide(SIW)can be adopted as one of the promising candidates for 5G to lower losses and realize high integration,as it combines both advantages of planar PCBs and nonplanar waveguides.In this paper,the principal parts include:Some brief reviews on fundamental principles of SIWs,scanned arrays,slot arrays and Butler matrix multibeam feeding networks(BMFNs)are performed,respectively.The four parts serve as an essential theory pillar for the subsequent prototype designs.Based on the aforementioned theories,designing techniques of SIWs,slot arrays and some analysis methods of BMFNs are combed systematically.To achieve a wide scanning coverage area and available radiation gains,a 4×4 BMFN is proposed for future 5G mobile applications.Under the uncertain background of the research,we select the multibeam scheme for 5G millimeter-wave antennas,since it has low complexity and wide coverage area.Combined with the features of the 5G mobile system,a 4×4 BMFN and a slot array which can be fully accommodated in the clearance area of mobile terminals are designed.The measurements and the data analysis show that the multibeam scheme can meet the requirements of future 5G terminal antennas in a certain degree.On the basis of the traditional 4×4 BMFN,an improved 4×4 SIW BMFN is proposed and designed.The feasibility of this scheme is theoretically proved at first and the restrictive conditions to each component are deduced correspondingly.The core concept to design the new BMFN is that the phase shifters are incorporated into the –3 dB hybrid couplers.The simulations and measurements illustrate that the improved BMFN exhibits better amplitude-phase flatness and design flexibility than traditional 4×4 BMFNs.A 3×3 BMFN is proposed.The design mentality is traced at the beginning of Chapter VII.Then,feasibility validations are provided and deductions of the 3×3 BMFN structure and the parameters of its components are detailed subsequently.The simulations and measurements show that the designed 3×3 BMFN possesses smaller size and simpler topology than the 4×4 BMFN,but has comparable gains and beam coverage area compared with the 4×4 BMFN.