Study On Base Station Antenna In Hybrid Heterogeneous Networks

Currently,the wireless communication industry has been in a critical stage of multiple networks(2G/3G/4G)co-existence,and Massive MEMO is being researched as therepresentative techniqueof 5G.As the front-end device of mobile communication system,base station antenna needs to meet multi-RAT requirement as well as good radiation performances.The antennas withadvantages of small size,broadband,multi-band,dual polarizations and Massive MIMO can solve various problems in the deployment of wireless networks,and provides a better choice for the operators.This dissertation describes the base station antennaelement with broadband and dual polarized performances,antenna element with multi frequency bands and dual polarizations,and the diagram ofvertical beamforming technology.In addition,Massive MIMO is fully studied and analyzed.The contributions of the study are summarized as follows:1.Broadband dual polarized base station antenna is studied.Two broadband antenna elements are designed,which operate in lower and higher frequency band,respectively.The using of meandered arms reduces the size and realizes the miniaturization design of the lower frequency band dual polarized antenna.The bends of the arms introduces the coupling between the adjacent dipoles,leading to broader bandwidth.The design of the high-frequency dual polarized antenna adopts the square patches,extending the path of the excited current.Meanwhile,the coupling between the two crossed dipolesthatimproves the real part of the impedance,makes the impedance changing with frequency varying smaller and widens the impedance bandwidth of the radiation element.Finally,the adoption of the feeding style combining coaxial cable and feeding pad achievesthefunction of tuning impedance matching bycuttingouter conduct part of the cable which soldered to the balun arms.This feeding style is very simple and easily to be applied to mass production.The antenna prototype measurement results show that two kinds of dual polarized antennas have good impedance and radiation characteristics and can meet the application demands very well.2.A compact dual band and dual polarized antenna is proposed.Research on the dual band and dual polarized antenna with interlaced form is performed.The high-frequency element is embedded in the low frequency element.A parasitic frame is used on the periphery of the low-frequency antenna to tune the beamwidth and gain of the high-frequency antenna.Based on the above researches,the construction of an antenna array with 5 low-frequency elements and 10 high-frequency elements is proposed.By bending the dipole arms,the low-frequency antenna element has smaller size and less effects on high-frequency antenna placed in it,which can reduce the array element space.High-frequency antennas are placed in the low frequency elements and the spaces between them.There is a plastic cover tuning the complementary characteristic of the beamwidth of the high frequency antenna element,which makes the beamwidth of dual frequency array antenna consistent in the horizontal plane.The measurement results show that the dual frequency band and electrically adjustable array antenna has good impedance and radiation characteristics.Therefore,it can meet the requirements of multi-system multi mode networking.3.A novel beamforming method for vertical plane of the radiation pattern of the complex electrically adjustable antenna is studied.Firstly,by combining electromagnetic simulation software and the genetic algorithm,the radiation pattern in the vertical plane of the antenna array is optimized;Then,based on the measured amplitude and phase data of the feed network,three typical relationships between the phases and the tilted angles are established;finally,the co-optimization for radiation patterns at multi angles is achieved by introducing the beamforming algorithm considering the inherent relatives between patterns.This optimized method can be used to the pattern optimization of the complex base station antenna,which can solve the problems such as angleaccuracy,gain loss,side lobe suppression in upper half-space and null filling of each tilted-angle pattern.We take a dual band and dual polarized antenna array as a sample and verify the validity of the design method by obtaining the large angle tilt pattern in the vertical plane in high-frequency band.The validity and efficiency of antenna design process are verified by the measurement results.4.The massive MIMO dual polarized planar array antenna is studied.Based on the ideas of integrated antenna element and modular sub-array,a 64 channels of massive MIMO dual polarized planar array antenna is designed.There are 32 RF channels for each polarization,which provide 32 degrees of freedom of amplitude and phase.Based on the electromagnetic simulation software and the genetic algorithm,the broadcast beamforming of large-scale active antenna arrayis analyzed and studied,and tradeoffs between the horizontal beamwidth and other design parameters are obtained,which providesreference significances for the active antenna array design of 5G communication system.