English Title Of Doctor Dissertation (Master Thesis)

With the explosive growth of mobile broadband services, the 4G-LTE system has been large-scale commercial deployed. The base station antenna is an important part of mobile communication system. However, the traditional narrow-band mechanical-tilt antenna is difficult to meet the demand of the network optimization. So broadband dual polarized electrical-tilt antenna is widely used in LTE system.In this paper a broadband dual polarized electrical-tilt base station antenna apllied in LTE system is developed.11 broadband dual polarized elements are used in this linear array. By optimizing the power divider network and 6ptimizing the initial feed phases using genetic algorithm, a shaped beam in vertical plane is realized. The side lobe suppression problem in the process of down-tilt is focused on. The experimental results show that the antenna array can realize electrical tilt from 0 degree to 10 degrees with gain larger than 18.5dBi and side lobe reducing below-16dB. The backboard structure with bilateral flanging is used and some key parameters are optimized to complete the design of shaped beam in azimuth plane. The experimental results show that in 1.7GHz-2.7GHz the horizontal beam width ranges from 65 to 69 degrees, the front to back ratio is above 25dB. And the cross polarization ratio is larger than 18dB in the main radiation direction, the cross polarization ratio within ±60 degrees is greater than 9dB, which meets the demand on the horizontal beam of base station antenna.Two broadband dual polarized radiating element including metal element and PCB element are used in the development of the array. The metal elment is fabricated by die casting technics.It works from 1.7GHz to 2.7GHz with the VSWR less than 1.59 and the isolation more than 30dB and the gain range of 8.88dBi-9.76dBi and a stable pattern. The printed element is fabricated by PCB technics.Two half wavelength radiation arms are crossly printed on both sides of the substrate to realize dual polarization. The frequency range of VSWR less than 1.5 is 1.62GHz-2.95GHz, the relative bandwidth is 58.2%. And the isolution is above 26dB. The gain range is 8.64dBi-9.29dBi and the pattern is stable from 1.7GHz to 2.7GHz.In addition, a 1 x 4 and a 2 x 2 small antenna array is designed using the printed element, and the S parameters and radiation pattern were tested.They agree well with the simulated results.