| In order to accommodate the growing needs of modern radar,wireless communication and electronic countermeasures for various ultra-wideband,doul-polarization,wide-angle scaning array antenna requirements,broadband and wide-angle scanning phased arrays are emerging.With the growing higher and higher requirements on their performance index,ultra-wideband phased arrays are becoming one of the research difficulties in various wireless electro nic systems in both domestic and overseas military and civil areas.Aimed at operating within 5 octave bandwidth of the ultra-wideband dual polarized phased arrays,this thesis studied a one-dimensional ultra-wideband dual polarized phased array based on an antipodal Vivaldi structure.The electromagnetic radiation and scattering characteristics of this ultra-wideband dual polarized phased array are also studied in detail.The main contents of this thesis are divide into four parts:Firstly,based on the theoretical analysis of the antenna model principle of proportional transformation principle of Vivaldi antenna,the antenna radiation principle dominated by the surface current distribution and ultra-wideband phased array theory are reviewed,thus laying a solid theoretical foundation of the succeeding antenna design.Secondly,in terms of imbalance to balance transformation feed of ultra-wideband antennas,a wideband,low loss and simple transformer of microstrip-to-slot-line is designed,A microstrip fan-stub with large angle to achieve broadband impedance matching is used.Moreover,the traditional forms of antenna element and antenna element based on the balance antipodal structure are also designed based on the designd balun.Comparison of simulation results show that modified antenna element maintained the same radiation characteristics as well as improved the cross polarization.Thirdly,dual polarization was futher realized based on the balance antipodal Vivaldi element.By using the periodic boundary conditions and radiation boundary conditions of electromagnetic simulation software HFSS,optimized simulation of the antenna array was performed,and a 10-element finite linear array was designed.Simulation results show that the designed array has fairly good antenna characteristics.Fourthly,the radar cross section(RCS)and antenna scattering theory were briefly reviewed.Monostatic RCS and bistatic RCS of the designed ultra-wideband phased array were simulated and analyzed,and numerical results were compared with those of a metal plate with the same area.It is found that the designed ultra-wideband phased array antenna has much better RCS characteristics than that of metal plate.Finally,the designed ultra-wideband array antenna was fabricated,assembled and measured for its radiation characteristics.Measured results are in good agreement with the simulation calculation results on the whole,thus effectively verifying the validity of the designde ultra-broadband dual polarized phased array. |
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