The Research And Design Of MIMO Antennas

The important development directions of mobile communication systems are high communication speed,wide bandwidth,and miniaturization.As one of the most critical components in modern short-range wireless communication systems,the ultra-wideband(UWB)MIMO(Multiple-Input Multiple-Output)antennas is hot research point.Focusing on this background,works have been carried out for miniaturized and high isolated UWB MIMO antenna.First a UWB MIMO antenna with microstrip line feed structure and coplanar waveguide(CPW)feed structure are proposed and analyzed.In this part of work,a new structure in combination with CPW-fed and surrounding ground is proposed,and Measures enhancing isolation of MIMO antenna,such as ground slotting and ground stub,are studied.Second,all the mentioned measures are applied to Asymmetric Coplanar Strips(ACS)to enhance the isolation of UWB MIMO antennas,and a new UWB MIMO antenna structure is optimized and designed to achieve good performance.The antennas are fabricated and tested to verify electromagnetic simulations.And the simulation and physical demonstration show good agreements.The main work of this article is as follows:1.A UWB MIMO microstrip antenna is designed.The operating frequency of the antenna covers the entire ultra-wide band(3.1-10.6GHz)defined by the FCC,and the isolation of the antenna is greater than 15dB within the working frequency range.The overall size of the antenna is 20×26×1.6 mm~3.2.To focus on the problem of compact UWB MIMO antenna a novel structure in combination with CPW feed structure and semi-surrounding ground is proposed and researched.The key researches discussed are the effect of different ground slotting methods and ground branches on the isolation of MIMO antennas.The influence of the semi-surrounded structure on the performance of the MIMO antenna is summarized through electromagnetic analysis,and the experimental verification of the compact UWB MIMO antenna are conducted.The operating frequency band of the antenna covers 3.1GHz to 12.7GHz,and the isolation between the two antenna elements is18dB.The antenna size is 18×22×1.6 mm~3.These results have been published at relevant conferences.3.The above measures for enhancing isolation are applied to Asymmetric Coplanar Strips(ACS),and a new structure of a UWB MIMO antenna with excellent performance is designed.The size of the antenna is 28×28×1.6 mm~3.The frequency band used by the antenna is 3.1-10.6GHz,and the isolation within the working frequency band is greater than 15dB.The works conducted this thesis have certain reference value for the antenna engineering.