Research On Wideband ±45° Dual-polarized Antenna For Base-station Applications

With the development of wireless communication systems,dual-polarization antennas have been widely used in base station systems due to their advantages of anti-polarization mismatching and strong anti-interference ability.Broadband antennas can cover multiple communication frequency bands and reduce the number of antennas,thus greatly saving the cost of communication systems.Therefore,the research of broadband dual-polarization is of great significance.Now that China has entered the 5G era,the 5G spectrum has been divided in China.In order to meet the 5G spectrum of China Mobile Unicom,China Mobile and China Telecom at the same time,the antenna bandwidth must cover at least 2.5GHz-4.9GHz,with a relative bandwidth of 65%.At the same time,with the arrival of 5G era,2G/3G/4G will not disappear immediately,but will coexist with 5G for a period of time.Therefore,it is very important to design an antenna that covers 2G/3G/4G and part of 5G frequency bands at the same time.In this thesis,the broadband dual-polarization antenna is studied,and three types of broadband dual-polarization antennas with relative bandwidth of about 75%are designed.The main contents of this paper are as follows:1?A differentially fed dual-polarizd antenna is proposed with multiple independently controllable resonant points.The antenna adopts the methods of adding parasitic plate,square ring and cutting U-shaped slots to make the antenna produce four resonant points.And the four resonant points can be adjusted independently in a certain frequency range.If we want the antenna to work in other frequency bands,it is very convenient to adjust.The simulated and measured results show that the antenna bandwidth covers 2.3GHz-5GHz when VSWR<2,the isolation degree is 27d B,the gain is about 7d Bi,the half-power beamwidth is 65±2°,and the antenna size is 0.55?₀×0.55?₀×0.23?₀.2?A diamond-shaped wideband dual-polarizd antenna is proposed.The antenna radiators are two pairs of diamond-shaped dipoles.The diamond-shaped dipole is formed after removing a trapezoid from the butterfly dipole.Compared with the previous butterfly dipole,one more resonant point can be added.At the same time,the parasitic patch is used for matching adjustment.Simulated and measured results show that the antenna bandwidth covers 1.66GHz-3.71GHz when VSWR<1.5,the isolation degree is 23.5d B,the gain is about8d Bi,the half-power beam width is 66±4°,and the antenna size is 0.56?₀×0.56?₀×0.32?₀.3?Two wideband dual-polarized antennas loaded with matching layers are proposed.The radiators of the two antennas are the same as those in Chapter 3 and Chapter 4,respectively.The matching layer of the first antenna is a dielectric plate with periodic metal holes.Using the matching layer,the standing wave ratio of the antenna in Chapter 3 can be reduced from less than 2 to less than 1.5.The simulated and measured results show that the antenna bandwidth is 76%from 1.66GHz to 3.71GHz when VSWR<1.5.The second antenna uses a periodic metal ring to adjust the matching.The antenna bandwidth is 74.8%from1.59GHz to 3.49GHz when VSWR<1.5.The isolation degree of the two antennas is more than 20d B,the gain and beamwidth are stable.