Research And Design Of Broadband Dual-polarized Base Station Antenna

Over the past two decades,we have witnessed a shift in mobile communications from 1G to 4G.During this period,the key technologies of wireless communications are changing,the amount of information processed is exploding,and the demands on the capacity and transmission rate of communication systems are also increasing.The base station antenna has an irreplaceable position and role in wireless communication,and its characteristics directly affect and restrict the performance of the wireless communication device.Recently,the MII?Ministry of Industry and Information Technology?has planned four bands for China's 5G technology R&D?research and development?test:Sub-6GHz:3.3³.6GHz,4.8-5.0GHz,and millimeter wave:24.75²7.5GHz,37⁴2.5GHz,but at present,China's research on 5G is focused on the Sub-6GHz band.The future trend of mobile communication systems will be the coexistence of 2G⁵G,and other communication formats.Therefore,research on a new type of base station antenna with broadband,multi-band,and miniaturization has become a hot topic.In this thesis,the research project is focused on the research of broadband,multi-band,and miniaturization of the mobile communication base station antennas,and the research background,significance,development status and trends of base station antennas are introduced.We have studied broadband and dual-band dual-polarization base station antennas by electromagnetic simulation software.The main research content includes the following aspects:Firstly,we studied a dual-polarization base station antenna covering 2G/3G/4G LTE bands?1710²690MHz?.A low-profile wideband dual-polarization high isolation base station antenna is proposed to solve the problems of narrow bandwidth,low isolation,and high cross polarization of existing base station antennas.In addition,the mechanism for achieving the above characteristics was studied and analyzed.Then,aiming at the two problems in dual-band dual-polarized base station antenna in existing literatures?The two bands are usually far apart and the bandwidth of the lower band is usually narrow?,two miniaturized dual-band dual-polarized base station antennas for Sub-6GHz of 5G application have been proposed.The first antenna is a compact dual-band dual-polarized antenna with filtering structures for Sub-6GHz base station applications.It is operating at the LTE?long term evolution:2500²690MHz?and Sub-6GHz?3300³600MHz?bands,where the center frequency of upper-band is 1.32 times of lower-band.By using the L-shaped and C-shaped filtering stubs to suppress the mutual coupling,the proposed antenna has a high port-to-port isolation between LB and UB?>25dB?,when the two operating bands are very close.We analyzed the characteristics of the resonators and their mechanisms of suppressing the mutual coupling between lower-band and upper-band elements.Finally,we have composed the above elements into a linear array.The two elements of the array are symmetrical about the reflector and have a small array width,which has advantages over the designs of other similar literatures.The second antenna achieves broadband of lower-band at small size,including impedance bandwidth and radiation pattern bandwidth.It is operating at the 2G/3G/LTE?1710MHz²690MHz?band and Sub-6GHz?4900MHz⁵800MHz?band.The overall size is only 0.41₀×0.41₀×0.45₀?₀ is the wavelength in vacuum at 2.2GHz?.The LB element is formed by two pairs of bent dipoles with a wavy edge to achieve broadband characteristics both on impedance bandwidth and radiation pattern bandwidth at a small size.