| With the continuous development of communication technology,people’s requirements for communication rate are gradually increasing,and the fifth-generation mobile communication technology came into being.Multiple-input multiple-output(MIMO)technology is one of the key technologies of 5G,which can significantly improve channel capacity.The channel capacity of the MIMO system is closely related to the number and correlation coefficient of transceiver antennas.However,as mobile communication devices not only need 5G antennas but also need to integrate antennas in different frequency bands to achieve various functions,the antenna design space of mobile phones is very limited.The limited space restricts the improvement of the number of MIMO antenna units,leading to strong mutual coupling and a large envelope correlation coefficient between antenna units,which seriously affects the channel capacity.How to deal with the contradiction between the number of MIMO antennas,the coupling between antenna units,and the limited design space are the key issues that need to be solved in the design of MIMO mobile phone antennas.Focusing on this key issue,three new decoupling methods are proposed and three kinds of high isolation MIMO mobile phone antenna arrays are designed through the study of MIMO antenna decoupling technology,in this thesis.The main work of this thesis is summarized in the following points:1.Aiming at the decoupling problem between a large number of antenna elements,a highisolation dual-antenna block that can be closely arranged is designed.Based on the proposed antenna module,a 16-element dual-band MIMO mobile phone antenna array is designed.The dual-antenna block includes a dipole antenna and a slot antenna.By using polarization orthogonal technology,balanced antenna,and grounding branch technology,not only the coupling inside the module is suppressed,but also the coupling between modules is reduced.The designed 16-element dual-band MIMO mobile phone antenna array isolation in the operation band is greater than 17 d B,the ECC is less than 0.11,and the 16×16 MIMO channel capacity is as high as 86.6bps/Hz.2.A self-decoupling antenna unit with a T-shaped structure is proposed,and an eight-element dual-band self-decoupling MIMO mobile phone antenna array is designed.The selfdecoupling principle of the antenna unit is verified by experiments that the coupling currents on the two arms of the T-shaped structure cancel each other out.According to the decoupling principle,the T-shaped structure is expanded into a dual T-shaped structure to operate in dual frequency bands.Based on the dual-band antenna,an 8-element self-decoupling dual-band MIMO mobile phone antenna array is designed.Without loading additional decoupling structures,the proposed mobile phone antenna array can obtain isolation of 19 d B only by the self-decoupling antenna itself.After fabricating and measurement,the ECC of the eightunit dual-band self-decoupling MIMO mobile phone antenna is less than 0.07,and the 8×8MIMO channel capacity is as high as 43.5bps/Hz.3.Aiming at the decoupling problem in the integration of different frequency antennas,a decoupling method combining the radiation structure of low/ middle-frequency antennas with the decoupling structure of high-frequency antenna units is proposed,and a multi-band MIMO mobile phone antenna array is designed.This decoupling method realizes the reuse of the radiation structure and the decoupling structure,which saves the design space of the mobile phone antenna.Three antenna units with different operation bands are designed to form a multi-band MIMO mobile phone antenna array,which covers nine communication frequency bands of low frequency(GSM850/ 900),middle frequency(DCS/ PCS/UMTS2100/ LTE2300/ 2500),and high frequency(Sub-6G/ Wi-Fi 5.5GHz).Among them,the Sub 6GHz MIMO antenna uses the proposed decoupling method,and the isolation can reach 18 d B.High isolations of MIMO antennas in other frequency bands are also obtained. |
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