Design Of Broadband Folded Reflectarray Antenna

In recent years,with the continuous developments of communication systems,different communication systems have different requirements on antenna performance.The planar reflector array employs a planar array of microstrip reflector units to replace the large curved parabolic reflector surfaces that are difficult to build.The microstrip reflector array is spatially fed with feeders,which avoids the complex feed network.Recently,the structure of folded planar reflector array has the characteristics of low profile and foldable,which has great advantages in reducing the payload of airborne antenna and realizing the integration of large diameter of array antenna.Therefore,the folded planar reflector array has become a research hotspot at home and abroad.In this paper,based on the working principle of folded reflection array,a single-layer subwavelength dual-polarization reflection unit based on double-opening resonant ring is designed by using the regulation effect of the structure of subwavelength hypersurface resonant ring on electromagnetic wave.The phase and polarization characteristics of the structure are analyzed in detail.Based on the continuity and discretization of the phase of the dual-polarization reflector,two folded reflector arrays were designed and the real objects were processed.The main research content of this paper will be briefly introduced as following:In this paper,a single-layer dual-polarization reflection unit is designed using a doubleopening subwavelength structure.In terms of polarization characteristics,high-efficiency polarization conversion can be achieved within 18 GHz-26 GHz of this unit.In terms of phase characteristics,the continuous phase change of 360° was realized by adjusting the deflating ratio of this unit,and the phase shift curves were parallel to each other,with good broadband characteristics.In addition,the phase discretization of 0°/180° is realized through the flip unit,and the phase error is small due to the same broadband characteristics.Then,based on the designed wideband dual-polarization reflection unit,this paper designs two wideband folded reflection array antennas based on continuous phase algorithm and discrete coding phase algorithm respectively.The hfss-matlab-api interface tool is used to realize the rapid modeling of the array plane.The 1-db gain bandwidth of the continuous phase and 1-bit folded reflection array reaches 26.7% and 30.8%,respectively,and the corresponding maximum gain is 23.9 d Bi and 20.5 d Bi,respectively.The simulation results are consistent.The phase quantization error is compared and analyzed by means of numerical simulation.In this design,1-bit quantization will bring 2.1d B gain error.Finally,a wideband folded reflection array element with adjustable phase and high polarization conversion efficiency is designed based on the double-opening resonant ring structure.The central frequency of this unit is 12 GHz,and the corresponding crosspolarization reflection coefficient of-3-d B relative bandwidth is 36.7%.The minimum polarization conversion loss in the passband frequency range is 0.78 d B.By introducing two switching diodes,the unit can be switched between 0°/180° and the phase error is less than 20°.Combined with the design of the choke circuit,the influence of the dc component on the antenna radiation is minimized,which provides the research foundation for the future realization of electronic beam scanning folded reflection array.