| The excellent spatial radiation RF characteristics of wireless communication terminals are a key factor in ensuring the quality of their communication transmission.With the widespread application of MIMO(Multiple In Multiple Out)technology,the importance of RF testing for multi-antenna mobile terminals has further increased.OTA testing(Over The Air Testing)has been widely recognized by academia and industry as a test that can accurately evaluate the overall communication capability of communication equipment.Mobile terminals can only be approved for listing if they meet the OTA performance indicators including TRP(total radiation power)and TIS(total omnidirectional sensitivity).With the increasing frequency range and complexity of functions of mobile terminals,the number of internal devices in the terminal has significantly increased,leading to serious deterioration of the electromagnetic environment inside the terminal.This will inevitably have an impact on the OTA performance of the entire machine.Terminal device manufacturers have an increasingly urgent need to regulate OTA testing parameters during design and improve overall OTA performance.Therefore,analyzing the main factors that affect OTA performance and optimizing terminal OTA performance through appropriate spatial layout adjustments has outstanding commercial significance,and conducting relevant research is extremely valuable.This paper aims to improve OTA performance by conducting in-depth research on the layout of key components on the board of 5G mobile terminals and their impact on OTA performance through on-board topology modeling,system level electromagnetic simulation,and practical testing.The main innovative contributions are as follows:1.A method was proposed to optimize the OTA performance of mobile terminals by adjusting the antenna spatial layout.In response to the problem of overall OTA performance degradation caused by an increase in the number of internal antennas in 5G mobile terminals,a reasonable spatial layout scheme is proposed to optimize the TRP and TIS of the terminal.On the basis of building a testing platform and designing a testing antenna,the paper adjusted the antenna spatial layout multiple times and conducted OTA tests on each layout scheme.Based on the test results,the impact of the spacing,coupling,and reflection coefficient between MIMO antennas on TRP and TIS was analyzed,as well as the reasons.Subsequently,various antenna layout schemes were tested again on human hand and head models to explore the impact of human body on the OTA performance of mobile terminals.Subsequently,effective measures were proposed to optimize OTA performance,including controlling antenna spacing,increasing decoupling structures,and adjusting antenna placement positions.On this basis,a multi band and multi antenna layout plan was designed that comprehensively considers various optimization measures,and OTA testing was conducted on it.The test results show that compared to not optimizing the layout,the OTA performance of this layout scheme has significantly improved:in free space,TRP has been improved by about 2 dBm,while TIS has been improved by about 3 dBm.When considering human influence,TRP has been improved by about 4 dBm,while TIS has been improved by about 5 dBm.Based on the method of adjusting the antenna spatial layout,the problem of optimizing terminal OTA degradation caused by antenna performance degradation in device dense environments has been solved.2.A method was proposed to improve the overall reception sensitivity of the entire machine by suppressing crosstalk generated by chips on the terminal board.To address the issue of reduced sensitivity of communication hardware systems due to the deterioration of electromagnetic environment caused by the dense distribution of key components on mobile terminal boards,an optimization approach is proposed to adjust chip layout and size to suppress crosstalk and improve TIS.On the basis of the traditional three-dimensional dipole model of chip radiation,the paper proposes an equivalent antenna model that is easy to simulate and study.Subsequently,research was conducted on the issue of crosstalk between chips and between chips and antennas on the mobile terminal motherboard.After completing the design of the electromagnetic simulation model,research was conducted on the impact of factors such as spacing,angle,and size on crosstalk.The simulation results indicate that the spacing between chips and antennas will have a significant impact on crosstalk between them.Reasonable spacing settings can achieve 20 dB and 15 dB crosstalk suppression,respectively.At the same time,it was found that the angle between chips and their own size will also have a certain impact on chip to chip crosstalk.Finally,based on the simulation results,a layout design approach was proposed to optimize crosstalk and improve the sensitivity of the terminal communication hardware system.The method of adjusting chip layout and size to solve the crosstalk problem has solved the problem of complex changes in reception sensitivity under the dense distribution of terminal motherboard devices. |
