| With the advent of the era of the “Internet of Everything(Io E)”,the communication requirements of massive users and devices have led to increasingly complex and diverse electromagnetic environments.In order to ensure the stable and efficient transmission of communication data,a large number of communication antennas need to be deployed on various platforms such as vehicles,ships,airbornes and satellites.Therefore,with the rapid increase in the number of user devices,low-cost and miniaturized design of communication antennas will undoubtedly be a key demand for future wireless communication systems.Benefiting from the flexible and powerful modulation ability of electromagnetic waves,metasurfaces are highly favoured in fields such as space exploration,electromagnetic stealth,and electromagnetic sensing.The planar air-fed array antennas(reflectarray antennas/transmitarray antennas)based on electromagnetic metasurfaces are high-gain antennas that combine the advantages of the traditional microstrip antenna and reflector/lens antennas,with a low profile,low cost,and easy fabricated,while avoiding complex feed network structures.They have broad application prospects in the future long-distance communication systems.This dissertation is based on a scientific research project,with the goal of miniaturization,high efficiency and multifunctional design of planar air-fed array antennas.Combining with the potential scenarios and practical application requirements,in-depth research is conducted around the dual-band dual-polarized folded transmitarray antenna(FTA),two-dimensional beamscanning FTA,metal-only FTA,and two-dimensional beam-scanning folded reflectarray antenna(FRA).The main contents and contributions of this dissertation are summarized as follows:1.Aiming at the actual demand of satellite communication systems on the performance of antenna bandwidth,polarization,and beam pointing,an antenna design method that integrates high-performance and compact structure is proposed.Firstly,a dual-band and dual-polarization with shared aperture transmitarray is designed,which has independent phase and polarization regulation capability in two bands.Then,based on the principle of folding the electromagnetic waves’ path,the effective reduction of the antenna profile height is realized by utilizing multiple adjustments of the transmitarray and the reflectarray.The measured results show that the antenna has independent beam control capability in the12 GHz and 15 GHz frequency bands,with measured peak gains of 25.28 d Bic and 24.88 d Bic,corresponding to total efficiencies of 28.2% and 16.5%,and a 3 d B gain bandwidths of approximately 8.8% and 9.1%.In addition,a dual-band dual circularly polarized FTA with vortex beams is designed on this basis,which radiates the beams with different orbital angular momentum(OAM)modes in two bands through a single physical aperture,improves the antenna aperture utilization coefficient.2.To address the issues that the traditional TA has a high profile,high dielectric loss,and difficulty in adapting to extreme environments,a low-profile metal-only FTA design method is proposed.The metal-only transmitarray based on the chiral metasurface is designed,achieving high transmission efficiency and 360° phase shift range through only two metal layers.In addition,the design without vertical metal structure reduces the thickness,processing cost,and complexity of the transmitarray.On this basis,a metal-only polarization-converted reflective surface is introduced to achieve multiple folding of the electromagnetic wave transmission path,further reducing the overall profile of antenna.The measured results show that the designed antenna has a gain of 27 d Bi at 12 GHz,corresponding to a total efficiency of 35.3%,and the 3 d B gain bandwidth is 14.6%.3.To solve the issues of high profile,limited scanning angle,and low aperture efficiency of traditional two-dimensional beam scanning transmission array antennas,a twodimensional beam scanning antenna design method based on FTA is proposed.A two-layer circular polarization-selective surfaces(CPSMs)with polarization selection and wavefront modulation functions is designed.Based on the principle of electromagnetic wave path folding,the antenna profile height is effectively reduced to only 1.92 λ0.On this basis,by independently rotating the two layers of co-axial CPSMs,the antenna beam achieves twodimensional scanning within the range of elevation angle 0～52° and azimuth angle 0～360°.The measured results show that the proposed antenna has a gain of 22.9 d Bic,corresponding to a total efficiency of 30.1%.The decrease in antenna gain during beam scanning is 3.4 d B.4.Traditional Risley Prism antennas are usually based on planar transmitarray antennas,and mostly utilize two or three layers of rotatable transmitarrays to achieve twodimensional beam scanning.To reduce the number of transmission array layers,a RisleyPrism antenna design method based on the FRA architecture is proposed.Firstly,a hexagonal transmitarray unit and a reflectarray unit are designed to improve the phase control accuracy of the array and provide the foundation for achieving two-dimensional wide-angle beam scanning.Then,the rotatable transmitarray and reflectarray are designed,by utilizing the modulation characteristics of electromagnetic wave polarization and phase,two-dimensional beam scanning capability is achieved with a lower profile.The gain of the proposed antenna is 19.3 d Bic at 16 GHz.The maximum scanning angle of the antenna in the elevation plane is 56.4°,and the gain decrease value when beam scanning is 3.9 d B.The measured results verify the feasibility of the design scheme. |
PDF Full Text Request