Research On Multi-antenna System For Mobile Phone Terminal

In order to meet the needs of modern communication equipment,the research and development of antennas is mainly carried out in several aspects,namely reduction in size,broadband and multi-band operation,and intelligent pattern control.As the integration of electronic devices increases,the size of communication devices becomes smaller and smaller.At this time,the antenna is too large for the entire device,which requires the antenna to reduce its size.However,reducing the size of the antenna while not significantly affecting the gain and efficiency of the antenna is a difficult task.With the increased integration of electronic devices,an antenna is often required to support two or more wireless services in a wider frequency range.Based on the antenna design method of power transmission maximization method,this paper designs a small eight-unit MIMO-smart phone antenna array covering 3300MHz-3500 MHz in Sub-6GHz.Secondly,an eight-element smart antenna covering the N78 frequency band(3300MHz-3800MHz)in Sub-6GHz was designed.At the same time,the reduction of SAR value was studied.The main research contents of this article are:1.Firstly,a small eight-element MIMO-smart phone array antenna was designed.The antenna array works at 3.3-3.5GHz in Sub-6G.It consists of eight three-dimensional inverted F antenna elements that share a common ground point.The antenna size,the antenna unit is only 5mmx5mmx5 mm.Through the neutralization effect of the shared ground point and the T-slot loaded on the ground,the mutual coupling between the antenna elements is less than2 mm and the mutual coupling is less than-10 d B.The maximum power transmission efficiency method(MMPTE)is used to obtain the optimal excitation distribution of the array antenna.Then use the digital phase shifter and attenuator connected to each antenna unit to achieve the optimal excitation distribution,so that the beam is deflected to the specified direction.The entire antenna is printed on the FR4 substrate,which occupies a small volume,and the S parameter is <-10 d B in 3.3-3.5GHz.The measured results are in good agreement with the simulation results.2.Secondly,an eight-element smart antenna that works in the N78 frequency band(3300MHz-3800MHz)is designed.The size of the antenna unit is 6.5mmx6.5mmx8 mm.The pattern of the antenna array in the x,y,and z directions can reach 2.9d B,7.9d B and 5.3d B,respectively.Applying the weighted maximum power transmission efficiency method(WMMPTE),introducing multiple receiving antennas,guiding the pattern of the antenna array,optimizing the near-field electric field distribution,and finally reducing the SAR value by about 30%.