Wideband Miniaturization Dual-Polarized Base Station Antenna

With the advent of 5G communication era,the coexistence of multiple communication standards is a long-term development trend of the communication systems in the future,which requires the communication system to have enough bandwidth to cover multiple standards.With the common development of several communication technologies(2G,3G,4G and 5G),the number of base station antennas has increased dramatically.Meanwhile,in order to achieve the compatibility of multiple communication systems,as the core equipment for network coverage of mobile communication systems,there are more and higher requirements for the base station antennas.Under the current situation of common development of multiple systems,the bandwidth of the base station antenna is required to cover multiple frequency bands of 2G/3G/4G LTE and 5G at the same time,so as to reduce the number of base station antennas.In addition,the base station antenna is required to be as small as possible,so as to facilitate flexible installation and environmental beautification.In order to meet the high requirements of modern mobile communication system and save space and resources,it is of great importance to carry out research on wideband miniaturization of base station antenna.The major contents of this paper are as follows:First,the first and second chapters present the background and significance of this study,and summarize the research history and present situation of wideband miniaturization of base station antenna at home and abroad.Then,based on the research and analysis of the current problems in the design of base station antenna and the future growing trend of the base station antenna,the research contents of this paper are put forward,which can cover3G/4G/5G low-frequency miniaturized base station antenna unit and 4G/5G broadband dual-polarization base station antenna unit.Then,on the basis of the previous research,a dual frequency combined base station antenna containing the latest 5G low frequency band is further proposed.The basic theory of base station antenna is briefly summarized.Secondly,a small dual-polarization base station antenna is designed.The antenna uses printed cross dipoles to realize double polarization.Each dipoles arm is curved petal structure,the arc structure will change the current path of the dipoles,making the low frequency resonance point move to lower frequency,in the meanwhile,it can change the coupling between the two polarization dipoles,making the high frequency resonant point move to higher frequency,so as to achieve the miniaturization and wideband of the antenna.Here,?-type coupling balun is used to feed the antenna,and the antenna can also be miniaturized by optimizing the size of balun reasonably.The size of the radiator of the antenna element is 0.31*0.31,and the height of the antenna is 0.15.It can achieve broadband coverage of 1880-3800MHz(VSWR<2.0),with a relative bandwidth of 67.6%,a gain of about 8.3d Bi,and the isolation of dual-polarization port is greater than 21 d B.Thirdly,a wideband miniaturization dual polarization base station antenna is designed.The antenna unit adopts the form of double polarization cross dipole,which is resemble with the above antenna.The current path of dipole is changed by using the coupling tangent structure of isosceles right triangle.The wideband of the antenna can be realized by reasonably controlling the coupling tangent and the coupling space between the dipoles.And the cross dipole is fed by microstrip?-type balun,the coupling feeding can effectively broadening antenna bandwidth.It can be achieved a good impedance matching by reasonably optimizing the size of the microstrip balun.The measured results suggest that the designed antenna can achieve the broadband coverage of 2300-5000MHz(VSWR<2.0),with a relative bandwidth of 74%and the gain of 7.3±1d Bi,which satisfies the demands of modern mobile communication system.Fourth,according to the wideband communication demands of the future 5G communication era for the mobile communication system,a miniaturized 698-790MHz low frequency antenna unit is designed.Based on the miniaturized low frequency antenna unit and the broadband antenna unit proposed above,a dual band small broadband dual polarization base station antenna composed of a low-frequency antenna element and a high-frequency antenna element is proposed,which can achieve the coverage of 4G/5G communication frequency band.