Research On Dual Polarized Cross Dipole Antenna

In order to meet the application requirements of modern science and technology,wireless communication systems are developing rapidly in the direction of miniaturization and broad-band.As a key component of wireless communication receiving and transmitting signals,the antenna directly affects the speed and quality of data transmission.Dual-polarized antennas have the characteristics of alleviating signal fading,reducing co-channel interference,and ex-panding communication capacity,so they are widely used in base station antennas,satellite navigation and other fields.Aiming at how to realize broadband of base station antennas and how to form a common interface and ultra-wideband for dual circularly polarized antennas,the following researches are carried out in this paper:(1)A broadband dual-polarization crossed multi-dipole base station antenna covering 2G/3G/4G is proposed.Through the coupling excitation of small dipoles and large dipoles on the dielectric substrate,new resonance points are generated at high frequency points to achieve the purpose of widening the bandwidth.The simulation and test results show that the size of the antenna is about 0.98₀×0.98₀×0.25₀,the impedance bandwidth of the antenna reaches63.7%(VSWR<1.5),the port isolation is greater than 27 d B,and the average gain is about 8d Bi,which can achieve dual-polarized radiation with good radiation performance.(2)A directional circularly polarized Yagi helix antenna based on a three-segment inverted helical structure is proposed.The proposed Yagi antenna consists of a driven element,a di-rector and two reflectors,and uses a coaxial line with a support as the feeding structure.After simulation optimization and processing test,the results show that the impedance bandwidth of the antenna is 5.42%(1.345 GHz-1.42 GHz),the gain can reach 7.03 d Bi,and the antenna array volume is 0.66₀×0.17₀×0.40₀to achieve a small size antenna.Then,two di-rectionally circularly polarized Yagi spiral array antennas are composed of a double circularly polarized yagi spiral array antenna structure to achieve the double circularly polarized radiation characteristics.(3)Using the design idea of a directional circularly polarized Yagi antenna with a three-segment inverted helical structure,a dual circularly polarized antenna array with an orthogonal structure is proposed.Eleven inverted helical antennas with different resonant frequency points are serially fed into a directional circularly polarized antenna array structure,and the two se-rially fed directional circularly polarized antenna arrays are crossed by taking advantage of the advantages of small inverted helical antennas inside and outside.The antenna array of the architecture uses double-sided parallel lines as the feed structure.The simulation results show that the impedance bandwidth of the antenna at port 1 and port 2 can respectively reach 1.58GHz-2.0 GHz and 1.40 GHz-2.20 GHz,and the axial ratio bandwidth can reach 1.40 GHz-2.0GHz and1.40 GHz-2.2 GHz.The array can continue to expand the number of helical elements to achieve ultra-broadband radiation characteristics.