Study And Design Of Broadband Base Station Antennas In Wireless Communication System

The base station antenna is a key component of the mobile communication network, it not only provides a link between the mobile station and a base station, but also is an important device for many mobile communication applications, such as frequency re-use, diversity reception, etc. With the rapid development of mobile communications business, we need to solve some new problem, such as, the scarcity of site resources, multi-path fading and so on. Therefore, it’s important to design the wideband and polarization diversity antenna, which can adapt to the operational requirements of different systems.In this thesis, the wideband and polarization diversity antennas for base station in wireless communication system are designed and investigated. Meanwhile, the simulation results are given. The thesis is divided into the following sections:Firstly, the research status of the base station antenna in wireless communication are presented. Then the radiation theory and analysis methods of the microstrip antenna, several important parameters, which describe the performance of antennas and the principle of selection are introduced.Secondly, a printed dipole antenna unit based on DSPSL structure is presented. The arms of the antenna element are printed in the upper and lower surfaces of the dielectric substrate and feed by double-sided parallel strip lines. This substructure makes the antenna has a wide bandwidth. Then, a linear array with8element is design and the reflector are added. The results show the proposed antenna can work in1.71GHz～2.67GHz with the maximum gain of17.2dBi. In addition, the half-power beamwidth of array antenna in the horizontal plane is64.7°and the gront-back ratio is greater than28dBi. This array can meet the requirements of a mobile communication system for rural areas.At last, a kind of dual-polarization array antenna fed with L-strip patch is presented. By using electromagnetic coupling and double-layers patch structure, the bandwidth of the antenna element is broadened effectively. The antenna element has a good radiation characteristics and gain. Then,4element linear array and the feed network are designed and optimized. The simulation results show that the antenna array can operate in the frequency range of1.74GHz-2.4GHz (VSWR<1.5) and its isolation S21is less than-20dB. At the same time, the antenna array has a half-power beamwidth of71°in the horizontal plane and the gain of13.5dBi. It is obvious that the antenna array has a good radiation performance and can meet the demand of the sector cellular mobile communication system in the dense urban area.