Research And Design Of Terminal Antenna For 5G Communication

5G(fifth-generation)wireless communication system is committed to providing users with network communication services with greater data capacity,higher data transmission rate and lower delay.The improvement of communication quality undoubtedly puts forward higher requirements for hardware devices.Mobile terminal antenna is the signal sending and receiving end of user equipment.As a key component of communication system,its performance directly affects the communication quality of the whole network.In order to meet the communication requirements in the 5G stage,present terminal antennas mainly face two challenges:on the one hand,the use of Multiple-Input Multiple-Output(MIMO)technology increases the number of antennas,while the miniaturization trend of terminal equipment reduces the design space of antennas,making antenna design more difficult.On the other hand,traditional spectrum resources are facing increasing tension,and it has become a general trend to develop new spectrum resources in the millimeter-wave band.Therefore,exploring a new type of terminal antenna for 5G communication has important research significance and application value.This thesis focuses on the research of terminal antennas in Sub-6GHz and 5G millimeterwave frequency bands,and the main works are summarized as follows:1.An 8-element MIMO antenna based on characteristic mode theory for Sub-6GHz band is proposed.Different from the traditional MIMO terminal antenna designs in which the antenna elements are arranged in sequence,a compact 2-element antenna pair is designed by using the method of characteristic mode analysis,which achieves both broadband and decoupling characteristics.By arranging four antenna-pair modules on the terminal substrate,the design of 8-element array is completed.On this basis,the defective ground structure is adopted to realize the isolation of more than 15dB between any two ports.The antenna can operate in 5G New Radio n77/n78/n79 and WLAN 5GHz bands,thus providing a candidate design scheme for the existing Sub-6GHz terminal antenna research.2.A dual-band shared aperture antenna that can be used in Sub-6GHz and millimeter bands is designed.In order to reduce the influence of metal ground on the radiation performance of high-frequency element,the low-frequency antenna element adopts the form of monopole antenna with only part of the ground.The double-layer radiation patch of monopole antenna is used as the SIW upper and lower metal plates of high-frequency quasi-Yagi antenna.On this basis,by loading a ring of metalized vias around the highfrequency element,the impedance matching of the low-frequency Sub-6GHz antenna and the isolation between the two ports are improved,while the original radiation characteristics of two antenna elements are not disturbed.The proposed dual-band design covers Sub-6GHz n77/n78 and 5G millimeter-wave n257/n258 frequency bands respectively,thus providing an effective design scheme for the compatible design of 5G millimeter-wave and Sub-6GHz antennas in future mobile terminals.3.A compact millimeter-wave 9-element antenna array satisfying vertical and horizontal dual polarization is studied.Firstly,a horizontally-polarized planar quasi-Yagi antenna and a vertically-polarized open SIW antenna are designed respectively.The elements have broadband characteristics and basically cover the n257/n258 bands of 5G millimeter waves.The design of 9-element array is completed by staggered arrangement of elements,which keeps compact size and achieves high isolation of any two elements.The designed array has good endfire characteristics and beam scanning capability.Compared with the current related designs,an integrated dual-polarization antenna with good performance is provided,which is expected to be applied in the future 5G millimeter-wave antenna design.