Research And Design Of Broadband Dual-polarized Base Station Antennas For Mobile Communications

The antenna as a device for energy transformation is irreplaceable in the mobile communication system,the good performance of base station antenna is the basic guarantee for the whole communication system to work normally,which directly affects the service quality of mobile communication.With the improvement of the quality of mobile communication,the requirements for antennas are also increasing,and base station antennas should have good circuit performance and stable radiation performance.Broadband,dual polarization and miniaturization are also important factors to design antenna.This thesis is based on the broadband and dual polarization to study and design the base station antenna that meets the LTE frequency band.First of all,a broadband ±45°dual-polarized printed dipole base station antenna is designed which is fed by double inverted-L probes,and the impedance matching of the antenna can be adjusted efficiently by cutting the angle of microstrip line,adding the branch and changing the width of the open branch.The antenna element is processed and measured,the results show that the antenna can cover the 1.7~2.7GHz frequency band and it has excellent performance in radiation pattern.he four-element array antenna is also simulated,and the effects of single layer flanged reflector and double flanged reflector on the radiation performance of the antenna is emphatically studied.Secondly,a double-layer printed ultra-wideband miniaturized base station antenna is designed.The tuning rods loaded at the end of the radiation arms can adjust the impedance matching,this antenna has a compact structure and it is promising for microcellular base station antenna applications.The structure parameters of the antenna are optimized and the measured results show that the proposed antenna achieves a bandwidth of about 55% from 1.65 GHz to 2.90 GHz for VSWR<1.5.Finally,a parasitic element is proposed based on the principle of horn antenna and Yagi antenna,which is loaded in the antenna above can effectively improve the antenna radiation pattern and gain.