Design Of Dual Broadband Dual-polarization 2G/3G/4G Base Station Antennas

The boom of mobile Internet service leads to a mounting increase of mobile users and traffic.The new generation of mobile communication system also has to feature a bigger capacity,higher transfer rate and better stability.As the mobile communication industry is in a situation where the 4G is entering the market in a large scale and many standards of 5G have not set yet.The 2G,3G and 4G(LTE)will be coexist for a long time before 2020.Taking into account the extremely scarce resources,network maintenance and the growing demand of mobile traffic,the base station antenna of current mobile communication system is deadly required to have a broadband,double polarization,multi-frequency integration,electrically adjustable downtilt,good performance of all aspects,high capacity,and can cover 2G/3G/4G simultaneously.Therefore,a dual-broadband,dual-polarization and with electrically adjustable downtilt base station antenna is designed in this thesis.It has not only important significance in research fields,but the market value and far-reaching significance in practice.Firstly,this thesis introduces the history of mobile communication and the research situation of the dual-broadband dual-polarization base station antenna both at home and abroad,then makes a simple instruction of multiple input multiple output(MIMO)technology and the basic problem of the linear array base station antenna.In addition,some key parameters of the base station antenna are presented in detail and corresponding service provider`s requirements is tabulated as well.Secondly,a novel low-frequency base station antenna element that operates from 698 to960 MHz is presented in this thesis.It`s like a octagonal bowl.It has three different kinds of parasitic plastic fasteners which not only improve its stability,but obtain a better impedance matching performance.Besides,the thesis proposes a crossed-dipole element with parasitic metal branches and parasitic metal stubs.It can cover from 1.7 to 2.7 GHz.Compared with the traditional crossed-dipole dipole like a rectangular ring,the impedance matching performance of the proposed antenna element is greatly improved.Finally,a dual-broadband dual-polarized antenna is designed for 2G/3G/4G base stations.It is composed of three rows,middle of which has 6 low-frequency elements,operates from698 to 960 MHz,with a relative bandwidth of 31.6% and others of which are comprised of 11high-frequency elements respectively,covers from 1.7 to 2.7 GHz,with a relative bandwidth of 45%.Since the left and right rows constitute a kind of MIMO antenna,the capacity of the mobile communication system which employs this design would be increased linearly and greatly.But most importantly,this antenna not only covers all of current communication systems,but has electrically adjustable downtilt(2 ° to 10 °),bringing great convenience for the adjustment and maintenance of communication network.In addition,the passive third-order intermodulation(PIM3)is briefly analyzed as well.