Design And Research Of Miniaturized 5G Base Station Antenna

With the rapid development of communication technology,the fourth-generation mobile communication system can no longer satisfy people's daily needs.Therefore,it is particularly important for antenna engineers to design base station antennas that can meet the fifth generation(5G)of mobile communication systems and have better performance.Miniaturized antennas have become an important development trend in the antenna industry due to their small size,light weight,low cost,strong wind resistance,and easy concealment.In order to pursue high signal-to-noise ratio and channel capacity,resist multipath fading,reduce space requirements and installation costs,dual-polarized base station antennas with high port isolation and low cross-polarization ratio have become the mainstream of development.In this paper,three base station antennas are designed according to the related requirements.Through simulation and measurement of antenna elements and arrays,the innovation and practicality of the antennas are verified.The first antenna is a miniaturized dual-polarized broadband base station antenna unit on a printed circuit board(PCB).The size of the antenna is 32mm × 32mm ×24mm(0.37 ?0 ×0.37 ?0 × 0.27 ?0,where ?0 is the central frequency wavelength),and the working frequency band covers part of the Sub-6 GHz(3.3GHz?3.6GHz)frequency band of 5G.The antenna consists of two coaxial cables for power feeding and a pair of vertically-placed T-shaped coupling feed structures to achieve its±45 ° dual polarization.The radiation patch is composed of two bent dipoles that placed vertically,which reduces the size of the antenna radiator effectively.In addition,the antenna adopts double-layer PCB structures,and the rectangular patch on the top layer broadens its bandwidth significantly.In the range where the antenna |S11| is less than-l0dB.The relative impedance bandwidth is 53%(2.41GHz?4.14GHz).The highest gain reaches 10.1dBi and the isolation is greater than 25dB.Meanwhile,the cross polarization level is more than 25dB.The antenna has the advantages of miniaturization,wide bandwidth,high gain and high polarization purity.The second antenna is a miniaturized±45 ° dual-polarized high-isolation base station antenna used in the 5G frequency band.By optimizing important parameters,an antenna unit with a working frequency band including 5G sub-6 frequency band(3.0GHz?3.91GHz)and a radiator size of only 28mm×28mm ×22.5mm(0.32 ?0 ×0.32?0 ×0.26 ?0,where ?0 is the corresponding wavelength of 3.45GHz)is finally obtained.In terms of power feeding,the form we use is staggered coupling feed,which can effectively improve the polarization isolation of the unit.Considering that base station antennas are often used in the form of arrays,the unit is assembled into array.The array spacing in the scanning direction is only 36mm(0.41 ?0)and wide-angle scanning performance of ±55° is realized.At the same time,the unit port polarization isolation,the same polarization isolation between the array elements and the cross polarization isolation between the array elements are all greater than 20dB,which shows that the array still meets the good isolation performance when it satisfies the wide-angle scanning.The third antenna is a miniaturized umbrella-shaped dipole phased array antenna based on double-layer Array-antenna Decoupling Surface(ADS).A pair of orthogonal deformed dipoles are used to form ±45° dual polarization,where each dipole corresponds to a polarization direction.The two arms of the dipole are designed to be bent,so that the length of the arms of the dipole is greatly reduced in the horizontal direction.So far,we have obtained a miniaturized dual-polarized umbrella antenna unit.The antenna unit is mainly composed of two dielectric plates,a pair of orthogonal umbrella-shaped dipoles and microstrip balun structures that printed on the dielectric plates,and a metal reflector.The size of the antenna is 19.8mm×19.8mm×23mm(0.23 ?0 ×0.23 ?0 ×0.26?0,where ?0 is the corresponding wavelength of 3.45GHz).When the array pitch is only 35mm(0.4 ?0),by adding a metal isolation wall,double-layer ADS and other decoupling structures,the antenna array can meet the index requirements of port polarization isolation,co-polarization isolation between array elements and cross-polarization isolation between array elements all greater than 20dB,and can reach the target of ±55° wide-angle scanning.