Research On Dense Multi-channel Dual-polarized Antenna And Its Time-Reversal Electromagnetic Characteristics

With the increasing demand for communication quality and communication rate,Multiple Input Multiple Output?MIMO?technology has become one of the core technologies of 4G?the 4th Generation?and 5G?the 5th Generation?communication.In recent years,base station antennas have mostly used dual-polarized MIMO antennas,mainly using its diversity gain and multiplexing gain to increase channel capacity,reduce multipath fading,and improve signal-to-noise ratio,thereby improving communication quality and communication rate.The increase in the number of antennas will increase the size of the antenna system,but the space resources of the base station are limited.If more antennas are arranged in the limited space,the coupling between the antennas will inevitably increase,especially for dual-polarized antennas.Therefore,the design of dense multi-channel dual-polarized MIMO antennas is extremely challenging.In order to arrange more antennas in a limited space and reduce the mutual coupling between the units,on the one hand,it is necessary to reduce the size of the antenna,on the other hand,it is necessary to design decoupling structure to ensure high isolation between the ports of the antennas.The adaptive space-time synchronous focusing characteristic of time reversal technology enables it to ensure the safe and independent transmission of information in a wireless communication system,and plays a role in improving communication quality.The designed dense dual-polarized MIMO antenna is used for time reversal communication to study its super-resolution focusing characteristics.The research work is innovative and practically valuable.In this thesis,we mainly studies the design of dense multi-channel dual-polarized MIMO antennas,and research the super-resolution focusing characteristics of the antennas.The main content of the paper is as follows:The first chapter mainly introduces the research background and significance of dual-polarization MIMO antenna and time reversal technology,and then introduces the research status of dual-polarization MIMO antenna and time reversal technology,respectively.The second chapter mainly introduces antenna-related theories,including the working principles of microstrip antennas and dual-polarized antennas,MIMO technology and antenna basic parameters,antenna miniaturization technology,and antenna decoupling technology.Finally,the experimental scheme of time-reversal super-resolution focusing characteristic of MIMO antenna is introduced.The third chapter introduces the design of dense multi-channel dual-polarized antennas,including the design of antenna unit,the design of two-unit and four-unit MIMO antennas.Firstly,a miniaturized dual-polarized antenna unit with high isolation and high cross-polarization ratio was designed based on slotting technology.Then,the antenna unit is composed of two unit MIMO antennas with a center spacing of 0.36?₀??₀ represents the free-space wavelength at the center frequency?.Three isolation structures:asymmetrical“V”short-circuited branch,slotting ground,and symmetrical“V”-shaped branch,are used to reduce the mutual coupling between ports.Furthermore,two-unit and four-unit dense dual-polarized MIMO antennas with center-to-center spacings of 0.5?₀and 0.36?₀ were designed to achieve high isolation and cross-polarization ratios.It shows that the designed antenna and isolation structure can be applied to MIMO antennas with different pitches and different numbers of antennas,and they all achieve good performance and are convenient to expand and have practical value.The fourth chapter introduces the time-reversal super-resolution focusing characteristics of dense multi-channel dual-polarized MIMO antennas.Using two different performance four-element dual-polarized MIMO antennas and reference antenna designed in third Chapter as target antennas to study the time reversal focusing characteristics of the target antenna to study the time reversal focusing characteristics of the target antenna,when the time-reversal mirror?TRM?antennas are single-polarized and dual-polarized dipole antennas.The fifth chapter summarizes the work done in the full text,and points out the shortcomings of the MIMO antenna design and time reversal super-resolution focusing experiments in the paper,and looks forward to the follow-up work.