Research On MIMO Antenna Technology For LTE Smartphone Applications

As the 4G LTE(Long Term Evolution) technology becomes mature and acquires rapid development, China has formally entered into the 4G era of the network, at the same time, and the strong market demands have greatly promoted the development of China’s intelligent machine industry. Combined with the user’s current actual needs, 4G smartphone not only needs to cover the LTE band, but also should be compatible with3 G, 2G network, therefore higher requirements of band coverage have been put forward for the 4G smartphones. Moreover, the LTE standard adopts the MIMO antenna technology, which will undoubtedly reduces the design space available for single antenna unit, greatly increasing the design difficulty of MIMO antennas for smartphones. At the same time, the limited space of smartphones and complex electromagnetic environments, make mutual coupling between the antenna units strong,which reduces the performances of the antennas and even affects the entire communication system. In view of the above challenges, wide band technology,decoupling technology and performance evaluation of MIMO antennas for LTE smartphones are studied in this paper, and four seven-band antennas will be put forward.Firstly, the research on the current situation of the antenna design for smartphones is made, and the market demand of the smartphones as well as challenges for MIMO antenna design are analyzed. At the same time, combined with the domestic and foreign research results, the mainstream decoupling technology and its typical application are analyzed. Then, the performance evaluation strategy of MIMO antenna and its main indexes are summarized.Secondly, this research mainly focuses on the study of matching circuit and reconfigurable technology, and their applications in wideband smartphone antennas.Using the two broadband technologies, two seven-band antenna for LTE smartphones have been designed, which can meet the demands for broadband coverage. The antenna parameters are optimized by the HFSS software, and then the antennas were processed and tested. Also, the relevant test data of the antennas are listed.Thirdly, based on the research of decoupling technology and wide band technology,a seven-band MIMO antenna fore WWAN/LTE smartphones applications is proposed,and the optimization, processing, testing and data analysis of the antenna are carried out.The results show that proposed MIMO antenna satisfies the design requirements. With a printing structure, the proposed MIMO antenna is also easy to be realized in practical applications.Finally, combined with the huge challenges of wide band multi-band decoupling, a hybrid decoupling scheme is proposed, which can meet the practical requirements of the wide band decoupling applications. Using mixed decoupling strategy, a small-size MIMO antenna covering WWAN/LTE is successful proposed. The experimental results show that the proposed MIMO antenna has stable performance, and can meet the actual demands of the LTE smartphones.