| With the rapid development of 3G technology in China, studies on the next generation mobile communication named as IMT-Advanced is becoming a hot spot. Moreover, as the most important component in the front of a mobile communication system, the base station antenna plays a key role in the entire system. Therefore, the study on the new base station antenna suitable for IMT-Advanced system is of more significance. This thesis presents some relevant studies on the base station antennas for IMT-Advanced system. The thesis mainly contains the following parts.Firstly, the significance and the status of studies on IMT-Advanced are introduced, and basic requirements for the base station antennas conform to IMT-Advanced are presented.Secondly, the design procedures of the base station antennas is described, such as the antenna parameters, titled angle, the rule of installation, the selection guide of base station antennas for different environment, the reflector design, etc.Thirdly, the antenna element is designed based on printed dipole with an integrated balun, according to the design principles of dipole antenna and balun. Meanwhile, using tapered or stepped structure, the bandwidth performance is improved at the lower and higher frequency band, thus satisfying the system requirements and laying a foundation for the design of antenna array at the next step.Fourthly, through the analysis and synthesis of an eight element linear array, a 45°linearly polarized linear array antenna is designed. A Z-shaped edge of reflector is adopted to broaden the beamwidth at the horizontal plane. Simulation results meets the design requirements.Finally, an eight element linear array with±45°dual polarization is designed, fabricated and integrated. Some techniques such as changing the type of reflector or adding the fences or coupled poles are adopted to control the beamwidth at the horizontal plane. Measurement results are in good agreement with the numerical simulation results, and they satisfy the design requirements. |
