Research On Wideband Base Station Antenna And Shaped-Beam Array Antenna

With the development of mobile communication system and the rapid growth of mobile communication traffic and business types, the stricter requirements have been proposed for the mobile communication base station antenna system. What's more, the development of 4G brings the updating of the base stations as well as the sharp increase in the number. In order to improve the performance of the base station antenna and solve the problem about location selection and large quantities of base station, it is essential to study on LTE and dual-frequency base station antenna. This thesis is summarized as follows:(1) The overview of background and development of mobile communication system and base station antenna is discussed. The circuit characteristics and radiation characteristics are analyzed in detail according to the actual application of base station.(2) Equivalent circuit analysis method of printed antenna is studied in chapter3. Then based on this method, a base station antenna unit applied to the GSM1800, 3G and LTE system is presented. Some broadband technologies, such as parasitic elements, broadband multi section balun and bow-tie design, are used to achieve the return loss <-15 d B while the bandwidth for 1580~2810MHz. Another broadband planar antenna using Rogers 4350 b with r? =3.66 and coupling fed by L-shaped balun is also presented. The bandwidth is 1690~3030 MHz, the gain reaches 9d Bi and the polarization is planar ? 45 ? which can effectively avoid the performance deterioration for antenna caused by array design.(3) A dual-frequency dual-antenna system applied to GSM900 and LTE system is studied in chapter4. The coaxial style is selected for double antenna array design after comprehensive comparison between side-by-side style and coaxial style. The 3-d B horizontal beam width is around 65 ? for high frequency and 85 ? for low frequency. This multi systems share one antenna can effectively reduce the number of antenna.(4) In chapter5, dual polarized antenna for LTE and dual-frequency array antenna are studied. The influence of the parameters on the antenna array is studied in detail. The design of antenna beamforming is realized by using genetic algorithm, which makes the first sidelobe in the top half below-18 d B and the first zero filling in the bottom half more than-20 d B to effectively solve adjacent cell interference and blind spot.