Novel Bow-Tie Antenna And Basestation Array Antenna For Mobile Communications

With the approaching of the third-generation mobile communications system (3G),it is foreseeable that the second-generation mobile telecommunication system (2G),3G and wireless LAN systems(WLAN)will coexist for a long period in China's mobile phone market in the future.Therefore,the multi-frequency band repeater antennas or broadband base station antennas are needed to be able to cover 2G/3G/WLAN,in order to meet the needs of Compatibility of different mobile communications wireless networks.In this dissertation,a bow-tie antenna working in the 2G/3G/WLAN bands synchronously is presented and designed,the electrical downtilt and beamfonning of the new microstrip base station array antenna developed by the team are also analyzed and researched.First,a double-sided printing new bow-tie antenna with asymmetric overlapped double arms is presented and designed,on the bases of analysis of known broadband bow-tie antennas.Two different feed modes,microstrip feed and coaxial feed are considered for the design,and the corresponding feed matching network is designed. Tests show that the antenna exhibits good performances on impedance characteristics and radiation patterns at the 2G band(824～960MHz),3G band(1.7GHz～2.2GHz)and WLAN band(2.4～2.5GHz),which meet the needs of mobile communications.The impact of arms overlapping on the work-band and arms asymmetric on the beam tilt are studied detailedly,and such antenna design methodology are also given.A new vehicle-mounted bow-tie antenna is analyzed and designed for the vehicle mobile communications,including the adjustable beam angle.In the study of new base station microstrip array antenna designed by the team, and the L probe-fed air microstrip base station antenna and arrays structure,the main beam electrical downtilt and the radiation patterns cosecant squared distribution integrated program of the actual array antenna is given,based on the electrical downtilt and beamforming of the linear-array antenna.The step of electrical downtilt is 0.1°,with the adjustment of 0°～25°,and the sidelobe under the half-space is below -20dB according to Dolph-Chebyshev polynomials.As to the beamforming,the Woodward-Lawson sampling is used for the line array cosecant squared integrated. The results including the current amplitude and phase of 4 elements,8 elements and 16 elements line arrays are obtained,and the vertical plane radiation patterns of the entire array is also contained,considering the impact of the given antenna element. The simulation results show that the integrated approaches are simple and effective.