A New Diversity Antenna For Mimo System

With the development of the mobile communication,frequency reuse and the traditional coding technology in 3G can't meet the needs of increasing number of subscribers and channel capacity of next generation. Presently,MIMO technology as a new concept is provided which explores the space resource,adopts the multiple antennas at both ends and space-time coding to obtain the multifold capacity without additional frequency bands.It is promising in the beyond 3G.The way to estimate a MIMO multiple antennas system is diversity performance.The thesis will bring forward a new antenna diversity scheme which can be applied in MIMO Base Station. Firstly,the author introduces the MIMO system and the basic concept of dversity summarily ,then goes into particulars a new type distributed antenna array which elements are monopole yagi antennas.The simulation and test results validate a very low correlaton of the received signals.Secondly,the author improves the distributed antenna array and gives the concept of the distributed switched antenna array for the first time.The antenna array will make each diversity branch receive almost equivalent signals and obtain satisfied diversity gain.Finally,the author indroduces a optimum circuit to amend the directivity pattern.The measurement data can reach the anticipate aim.To enhence gain,the author adopts four dipole yagi antennas to form a arry along z axis and offers the corresponding experiment results.