| With the development of 5G technology,the high data transmission rate of mobile terminals has become more and more important,so mobile terminal MIMO antenna technology has increasingly become a research hotspot.The current mobile terminals are developing towards a trend of high screen-to-body ratio,ultra-thin,narrow bezel,metallization,and multi-function.This makes the space left for the antenna smaller and smaller.The mutual coupling of antennas in compact spaces is a difficult problem.Therefore,how to place more antenna units in the very limited internal space of mobile terminals and reduce Coupling between small antenna elements is a great challenge.In addition,the miniaturization of antennas,broadband,and multiple frequency bands are also important research directions.This paper will focus on reducing the mutual coupling between MIMO antennas.The main work can be summarized as follows:First,a self-decoupling 8-element MIMO antenna is designed,the working frequency band covers 3.4-3.6 GHz,and the reflection coefficient is less than-6 d B.The antenna unit is an inverted U-shaped grounded radiating element,two additional rings,and a T-shaped coupling feed element.Without adding any external decoupling structure,the decoupling of the antenna is realized by self-isolation decoupling.The isolation of the antenna is greater than 21.2 d B,and the channel capacity is 35-37.5 bps/Hz.In order to carry out miniaturization design and increase MIMO antenna channel capacity,the above-mentioned 8-element MIMO antenna is optimized and improved.The antenna is changed from 8 elements to 14elements,and the size of the antenna element is reduced from 17.5×6 mm~2 to14.6×6 mm~2,and The isolation is greater than 13.5 d B,and the channel capacity value of the antenna is increased to 55.5-59 bps/Hz.Listed in the frequency band3.4-3.6 GHz,the performance comparison between the two antennas proposed in this chapter and the antenna in the reference.By loading a human hand model on the MIMO antenna,the performance of the mobile terminal MIMO antenna in practical applications is simulated.This paper also processed a 14-unit self-decoupleing MIMO antenna and tested its S-parameters.The S-parameter results of the physical antenna are consistent with the simulation results.Secondly,a 16-element MIMO antenna decoupled by grounding stubs and floor gaps was designed.The working frequency bands are 3.4-3.6 GHz and 4.8-5GHz.The antenna unit adopts a double U-shaped ring structure.The antenna decoupling is achieved by adding a floor branch in the antenna U-shaped unit and slotting between the antenna units,and the isolation of the antenna is greater than13 d B.Listed in the frequency band 3.4-3.6 GHz and 4.8-5 GHz,the performance comparison between the antenna proposed in this chapter and the antenna in the reference.The performance of the antenna after loading the human hand model is analyzed.A 16-element MIMO antenna was processed and its S parameters were tested.The S parameter results of the antenna are different from the simulation results,and the reasons for the errors are analyzed through simulation... |
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