The Study About The Decoupling Of LTE Multiple Antenna System And Antenna Design

LTE system is an important technology that modern 3G communication run into 4G. In order to meet the requirement of high communication rate, LTE have used multiple antennas technology. The use of multiple antenna technology, greatly enhances the communication capacityof the antenna system. However, in terminal system, multiple antenna often distributed in a limited space, and antennas usually spaced between one-tenth wavelength. This makes larger couplingbetweenmultiple antenna, but the capacity of the antenna is closely related to the correlation coefficient of the antenna system, while correlation coefficient of the antenna system has close relation to the coupling of the antennas. So how to reduce the coupling between the antenna became a importantpromble. In order to reduce the couplein of antenna, this paper give the orthogonal radiation pattern from S parameters,and found the we can reduce the coupling between the antennas adding to a decoupling network between feeders network. And coupling network can be gived througha changing of unitary matrix of the orthogonal model.And it can be found that we can eliminate the coupling of a two antenna system when using a 90 degree orthogonal hybrid network couplers, and this kind of orthogonal hybrid network has a simple structure and is easy to implement.In order to verify the theory that we have given, the paper designed a LTE double antennas system working at 700M Hz and a LTE double antennas system working at 2.3 G Hz. Then wegive a simulation about the antenna system useing electromagnetic simulation software HFSS. The results showed that in the case of two antennas relatively close, if we did not make any decoupling processing between themicrostrip antennas S12 and 521 is usually below -5dB, while using a decoupling network between two antenna, the coupling decreased.So the decouping technology satisfies the requirement of multiple antenna systems communication.In addition, this paper also discusses the near field coupling and mechanism of surface wave emergence about the patch antennas. We found that we can eliminate the coupling of the antenna system from surface waves and near field if we don't use coaxial feeding and appropriately increase the distance of themicrostrip patch. Then we design a double antennas system working at 3.4 GHz.And using embedded microstripfeeding and slotingstructure,the volume of patch antennas can eliminate and reachs good matching. Using the electromagnetic simulation software HFSS,wecan found that the two ports antenna system can achieve good isolation.