Research And Design Of The Differentially Fed Base Station Antenna

As the last stage of the mobile communication system,the base station antenna plays a vital role.In recent years,the design and innovation of broadband,multi-frequency,and filtering characteristics have become important research topics and directions in the field of base station antennas.Circularly polarized antennas are used in many communication systems due to their excellent characteristics of reducing multipath fading and polarization mismatch.Therefore,the design of the base station antenna used in the mobile communication system as a circularly polarized antenna also has extremely important research significance.Differential feeding is frequently used in the design of microstrip antennas because of its features of common-mode rejection and ease of integration.In particular,differential feed is a balanced feeding mode that reduces the use of baluns and can be applied to the design of base station antennas.In this paper,the related technologies such as differential antenna,circular polarization,wideband,multi-frequency and antenna filter characteristics are studied.Combined with the technical characteristics and advantages,several base station antennas with excellent performance are designed,as follows:1.A differentially fed broadband circularly polarized antenna is designed.The antenna achieves better common mode rejection through differential feeding.A circular phase shift structure is used to achieve phase quadrature of the crossed dipoles to achieve circular polarization.The axial ratio bandwidth is broadened by placing a parasitic patch around the feeding structure of the antenna.A wide impedance bandwidth is achieved by the optimizing the design of the structure of the antenna radiator.2.A differentially fed dual-frequency dual-polarized base station antenna is designed.The antenna uses two pairs of differential ports to feed the crossed dipoles,achieving great common mode rejection characteristics and port isolation characteristics.The antenna uses nested ring radiation structure to achieve dual-frequency operation,and it has a wide impedance bandwidth,covering all working frequency bands of 3G/4G and 5G working frequency bands of 4.8GHz-5GHz.3.A differentially fed broadband antenna with filtering characteristics is designed.The antenna uses a microstrip line as to feed the base station antenna.The microstrip lines are fed by two pairs of differential ports.The introduction of the resonant branches on the microstrip feeding structure allows the antenna to have filtering characteristics and broaden the bandwidth of the antenna.The out-of-band rejection characteristics of the antenna is enhanced by etching the resonant slots on the radiating structure.