Studies On The Techniques For Miniaturized Broadband Base Station Antennas

As the core device of mobile communication network coverage, the base stationantenna is an important component of a mobile communication system. With the rapiddevelopment of3G/4G mobile communication network, higher demands are being puton the performance of base station antennas. Nowadays, the base station antennas areevolving with the trends of broadband, multi-band and miniaturization. Thus,microstrip antenna and printed dipole antenna which have demonstrated merits ofsmall size, light weight, easy fabrication and integration, have become the primarychoice in the design of a base station antenna. However, these antennas inherently havea narrow-band characteristic. In the traditional designs, the reduction in physical sizeinevitably leads to a significant degeneration in the antenna performance. Therefore,the design of base station antennas with the characteristics of wideband, small size andlow profile becomes the major issue nowadays.This thesis is mainly focused on the miniaturized antenna array design for theapplications of LTE wideband mini base station, dual-band dual-polarization mini basestation, and broadband wide-beam base station for IMT-Advanced system, with somerelevant experimental verification. The main contents of the thesis are as follows:Firstly, the development of base station antennas and the significance of studieson miniaturization of base station antennas are presented. Some detailed requirementson base station antennas of those three types of applications are also summarized.Secondly, the basic theory of base station antennas and concepts including beamtilt, beam forming are described. Some methods on suppressing mutual coupling inarray environment are also presented.Thirdly, a compact dual-polarized microstrip patch antenna for LTE mini basestation application is designed, and a2x4array is then designed based on the patchantenna element. Some methods for electromagnetic shielding of the feed network andmutual coupling suppressing are also described. Measured results are presented toverify the feasibility of the design.Fourthly, a2×2microstrip patch array with characteristics of miniaturized size and low profile for3G dual-band dual-polarized micro base station is presented. Thefeasibility of the design is verified through simulation.Finally, focused on the demand of the IMT-Advanced system, a broadband widebeam dual-polarized printed dipole antenna is designed. The dipole structure are easyto be integrated with the feed network A4×10compact planar array is then designedand manufactured using the dipole antenna. In order to achieve beam down tilting andside-lobe suppression, a broadband unequal power divider network is designed andoptimized. Experimental results show that the planar array antenna has very goodelectrical performance.