The Design And Implementation Of Ultra Wide Band Dual Polarized Antenna

As the electromagnetic signal environment becomes more complex,the performance of radar reconnaissance equipment is improving gradually.Dual-polarized technique can receive all polarized information of electromagnetic wave at the same time,with the capacity of anti-jamming,polarization multiplexing and polarization agility.Ultra-wideband technique has the advantages of the capacity of anti-jamming and good concealment.The performance of the antenna plays a key role in the radar reconnaissance system.Radar reconnaissance system can improve the performance of system by adopting ultra-wideband dual-polarized antenna.According to the application background of radar reconnaissance,this paper designs dual-polarized antennas for radar reconnaissance system.The primary contents of the dissertation include:(1)A complementary log-periodic ultra-wideband dual-polarized antenna.The working frequency of radar reconnaissance system is the range of 2-18GHz.A dual-polarized log-periodic antenna is designed which the working principle is the principle of duality.When the distance between the electric dipole and the magnetic dipole is ?/4,the complementary characteristic is best.The dual-polarized antenna is orthogonal at any point in space.The dual-polarized antenna has low profile,high port isolation and low cross-polarization.The working frequency of the antenna is the range of 0.8-18GHz.The isolation of two ports is 34.06dB and the cross polarization is-22dB.The complementary log-periodic ultra-wideband dual-polarized antenna is realized with the electric vectors orthogonal in the whole space in theory when ?=00.The volume of the antenna is half that of other dual-polarized log-periodic antenna.The simulation results are consistent with the theoretical analysis.(2)An ultra-wideband dual-polarized Vivaldi antenna with improved Balun.Due to the large volume and mass of the designed dual-polarized log-periodic antenna,it is not conducive to practical application.Therefore,the dual-polarized Vivaldi antenna is proposed.The antenna adopts the design method of impedance matching.The novel Balun structure consists of slot line and curved coplanar strip line.By the method of angle cutting,the current distribution of the antenna is charged to improve the isolation of the two ports.The working frequency of the antenna is the range of 2-8.834GHz.The isolation of two ports is 15dB and the cross polarization is-15dB.The antenna is orthogonal in-24°?28°.The experiment results show that the test results agree with the simulation results.Although the volume and mass of the dual-polarized Vivaldi antenna are smaller than the dual-polarized log-periodic antenna,the working bandwidth is narrower.(3)An ultra-wideband dual-polarized antenna based on slot-ferrite.Ferrite material has the characteristics of high magnetic conductivity and high dielectric constant,which is helpful to reduce the antenna size.As the bias magnetic field increases,the magnetic resonance peak moves towards high frequency.Firstly,the theoretical formula of the rectangular FRA working in TE mode is analyzed.According to this formula,a linear polarized FRA with coaxial feed is modeled.Then,asymmetric structure is adopted to realize the dual-polarized antenna.the mode of feeding of another port adopts electromagnetic coupling from micro-strip line to slot line.The working frequency of the antenna is the range of 2-18GHz.The antenna is orthogonal in-72°?0°.The simulation results are consistent with the theoretical analysis.The structure of antenna is so small.The simulation results meet the design index.