Research On OAM Reflectarray Antenna And Its Curved Radome

The use of vortex electromagnetic wave radar,which utilizes orbital angular momentum(OAM)beams with a helical phase wavefront structure,provides a unique advantage in the detection and recognition of targets,as it acquires more target scattering information than a planar wave.The modern intelligent applications demand high-frequency efficient deflection and working bands for the vortex electromagnetic wave radar,which can be achieved through the design of OAM antennas and their radomes.In this regard,this study focuses on the wideband,high-efficiency deflection of OAM beams and the design of frequency selective surface(FSS)radomes for vortex electromagnetic wave radar systems.Combining Pancharatnam-Berry(PB)phase,perfect anomalous reflection,and FSS theory,this study investigates OAM reflectarray antenna and its curved radome.Firstly,the design of the wideband OAM reflectarray unit is studied.Based on the requirements of PB phase and reflection phase shift,a sub-wavelength basic unit with a low profile is determined for the reflectarray.The U-shaped slot multi-resonance structure is constructed and optimized using equivalent circuit theory,and the wideband circular polarization characteristics of the unit are verified through Floquet theory simulation.Secondly,based on the design of the wideband reflectarray unit,the compensating phase distribution of the OAM deflection beam generated by the unit arrangement is constructed.This includes compensating the vortex phase of OAM mode number 2,compensating the feed source phase introduced by small circular polarization feed sources,and compensating the gradient phase of beam deflection.Combining perfect anomalous reflection theory,a compensating calibration method is proposed using unit rotation fine-tuning to compensate for nonlinear phase and improve beam deflection efficiency.Then,the far-field and near-field simulation results of the OAM reflectarray antenna are analyzed,and the beam deflection error and OAM mode purity are calculated.The calculation results show that the designed OAM reflectarray antenna generates a high-purity,wideband circular polarization OAM beam with mode number 2.Finally,the design of the curved frequency selective radome for the reflectarray antenna is studied.The radome unit is determined to be an A-layered structure with low-resistance highpass FSS units.Using the super-ellipsoid family equation to fit the surface spline,the radome model is established and its electrical performance,frequency selection performance,and OAM beam radiation performance are calculated.The results show that the designed radome has good power transmission performance within the passband,low bore sight error,small distortion in the pattern,and effectively reduces radar cross-section.In conclusion,this study investigates the wideband,high-efficiency deflection of OAM beams and the design of frequency selective radome for vortex electromagnetic wave radar systems.Through the wideband design of OAM reflectarray unit,construction of compensating phase distribution,analysis of simulation results,and design of curved frequency selective radome for reflectarray antenna,the generation of high-efficiency deflection wideband OAM beams is achieved.The simulation results confirm the feasibility of the proposed design scheme,providing powerful support for the development of vortex electromagnetic wave radar technology.