Analysis And Design Of 5G Mobile Terminal Antennas

The fifth generation(5G)mobile communication system is not only the reflection of highspeed,low delay,multi-device access and over the air technologies,but also the evolution of intelligent network for business applications and user experience.And driven by the demand of high-speed and high-density data transmission,wireless communication system also needs to provide more abundant channel capacity and higher spectrum utilization.With the smart terminals continuously enriching their functions,the antenna system needs to be upgraded,as it is the key component of information exchange.In order to comply with the development trend of terminal equipment and improve the channel capacity and spectrum utilization of wireless communication system,this paper designs several antennas for 5G mobile terminals in Sub-6GHz and millimeter wave frequency band,respectively.Firstly,aiming at the problem of strong electromagnetic coupling between MIMO antenna elements,this paper adopts loop antenna and monopole that fed by capacitive coupling,and based on the ideas of choke and cancellation,designed three multi-unit MIMO antennas that operating at 3.5GHz frequency band(3.3GHz-3.6GHz).In the design of MIMO antenna by loop element,the different decoupling mechanism of ground slot and neutralization line are adopted to realize the decoupling design of multi-elements,and a good isolation of more than 15 d B is obtained finally.For monopole MIMO antenna,the folding technology and three-dimensional structure layout are used to realize the miniaturization design.And then,the isolation performance of the elements are optimization by using the slots structure and the parasitic branch synchronously.The final results show that the proposed MIMO antenna covers the 3.5GHz band,and a good isolation is obtained,the ECC is less than 0.3.Therefore,the MIMO antenna designed in this paper has good performance,which can be used as an effective alternative to 5G terminal mobile antenna.Secondly,according to the requirements of different communication functions of terminal antenna,two shapes eight-element dual-band MIMO antennas working in different bands are designed by using dual branch structure and hybrid antenna forms.The working characteristics of the dual branch unit at high and low band are controlled by different branches,which cover the 5G medium band of 2.6GHz band(2.5GHz-2.7GHz)and 3.5GHz band(3.3GHz-3.6GHz),respectively.And then,a good isolation more than 15 d B between MIMO elements is obtained by adopting the parasitic patch structure;While,the dual-band antenna mixed with IFA and floor Loop branch realizes a good coverage of 3.5GHz band(3.4GHz-3.6GHz)and 4.9GHz band(4.8GHz-5.0GHz).In addition,the combination of “?” shape ground branch and orthogonal polarization technology are adopted to improving the isolation between elements,which bring the isolation in the high and low band over 15 d B and 18 d B,respectively.Thus,the dual-band eight element MIMO antenna designed in this paper improves the spectrum efficiency effectively,so the MIMO array have a good application prospect in the design of 5G smart terminal antenna.At last,with regard to the situation of spectrum resource shortage in Sub-6GHz band,two kinds antenna elements with superior performance are designed in millimeter wave band by adopting SIW slot coupling feed technology,which combin with the form of dielectric resonator antenna(DRA)and magneto-electric dipole antenna(MEDA).The wide band and high radiation efficiency DRA element design is realized by utilizing the good waveguide transmission characteristics of SIW and the good field characteristics of dielectric resonator.While in the MEDA structure design of SIW feeding,the chamfering and meandering technology are used,which not only realizes high gain and stable radiation pattern,but also expands the bandwidth of antenna unit,and finally achieves a good coverage of 24.09GHz-30.47 GHz band,and the relatively bandwidth reaches 23.4%.In addition,this paper also analyzes the beam scanning performance of millimeter wave array based on the phased array theory,and adopt the Butler matrix as the feed network to study the spatial beam coverage of the MEDA millimeter wave array.The result shows that the half power lobe angle in the azimuth plane of the millimeter wave array can achieve beam coverage within ± 50 ° at the whole operation band.Therefore,the two millimeter wave antenna units and arrays designed have good application prospect in 5G terminal equipment.