Coding metasurfaces make it possible to manipulate electromagnetic(EM)waves digitally by means of several discrete particles.Hence,there have been rapid advances in this field recently.Here we propose a novel design o...Coding metasurfaces make it possible to manipulate electromagnetic(EM)waves digitally by means of several discrete particles.Hence,there have been rapid advances in this field recently.Here we propose a novel design of a broadband transmission-type coding metasurface,which is valid to both x-and y-polarized EM incidences from 8.1-12.5 GHz while satisfies the requirements of 1-bit coding without changing the polarization.Two types of multi-layer coding particles with different geometrical parameters are adopted to represent the digital states"0"and"1",which are easily promoted to terahertz and optics through modifying the size scale.To verify the ability to manipulate the EM waves,we first adopt the coding metasurface to achieve broadband beam forming by converting spherical waves to plane waves and realize high-directivity pencil beam in far field with low side lobes.We further arrange the particles according to the coding sequence 010101…to steer two symmetrical beams in different directions controlled by frequencies with the maximum range of the scanning angle of 30°-50.5°.The good agreements between the simulated and measured results validate the proposed broadband coding metasurface,indicating its huge potential in communication and radar imaging systems.展开更多
To the problem of the unknown underwater target detection, according to the feature that the underwater target radiated noise contains the stable line spectrum, a weighted method based on the main-to-side lobe ratio ...To the problem of the unknown underwater target detection, according to the feature that the underwater target radiated noise contains the stable line spectrum, a weighted method based on the main-to-side lobe ratio （MSLR） is proposed for broadband beam-forming. This weighted method can be implemented by using the following steps. Firstly, optimize the spatial spectrum of each frequency unit by the second-order cone programming （SOCP）, and obtain the optimized spatial spectrum with lower side lobe. Secondly, construct weighting factors based on the MSLR of the optimized spatial spectrums to from weight factors. Lastly, cumulate the spatial spectrum of each frequency unit via the weight statistical method of this paper. This method can restrain the disturbance of background noise, enhance the output signal-to-noise ratio （SNR）, and overcome the difficulty of traditional four-dimensional display. The theoretical analysis and simulation results both verify that this method can well enhance the spatial spectrum of line spectrum units, restrain the spatial spectrum of background noise units, and improve the performance of the broadband beam-forming.展开更多
基金supported by the National Key Research and Development Program of China(Grant Nos.2017YFA0700201,2017YFA0700202,and 2017YFA0700203)the National Natural Science Foundation of China(Grant Nos.61631007,61731010,61735010,61722106,61701107,and 61701108)+4 种基金the Fund for International Cooperation and Exchange of the National Natural Science Foundation of China(Grant No.61761136007)the Overseas Expertise Introduction Project for Discipline Innovation(Grant No.111-2-05)the Fundamental Research Funds for the Central UniversitiesPostgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX17_0092)the Scientific Research Foundation of Graduate School of Southeast University(Grant No.YBJJ1815)。
文摘Coding metasurfaces make it possible to manipulate electromagnetic(EM)waves digitally by means of several discrete particles.Hence,there have been rapid advances in this field recently.Here we propose a novel design of a broadband transmission-type coding metasurface,which is valid to both x-and y-polarized EM incidences from 8.1-12.5 GHz while satisfies the requirements of 1-bit coding without changing the polarization.Two types of multi-layer coding particles with different geometrical parameters are adopted to represent the digital states"0"and"1",which are easily promoted to terahertz and optics through modifying the size scale.To verify the ability to manipulate the EM waves,we first adopt the coding metasurface to achieve broadband beam forming by converting spherical waves to plane waves and realize high-directivity pencil beam in far field with low side lobes.We further arrange the particles according to the coding sequence 010101…to steer two symmetrical beams in different directions controlled by frequencies with the maximum range of the scanning angle of 30°-50.5°.The good agreements between the simulated and measured results validate the proposed broadband coding metasurface,indicating its huge potential in communication and radar imaging systems.
基金supported by the National Natural Science Foundation of China(Grant No.61372180)the National Key Scientific Instrument Equipment Development Project of China(Grant No.2013YQ140431)
文摘To the problem of the unknown underwater target detection, according to the feature that the underwater target radiated noise contains the stable line spectrum, a weighted method based on the main-to-side lobe ratio （MSLR） is proposed for broadband beam-forming. This weighted method can be implemented by using the following steps. Firstly, optimize the spatial spectrum of each frequency unit by the second-order cone programming （SOCP）, and obtain the optimized spatial spectrum with lower side lobe. Secondly, construct weighting factors based on the MSLR of the optimized spatial spectrums to from weight factors. Lastly, cumulate the spatial spectrum of each frequency unit via the weight statistical method of this paper. This method can restrain the disturbance of background noise, enhance the output signal-to-noise ratio （SNR）, and overcome the difficulty of traditional four-dimensional display. The theoretical analysis and simulation results both verify that this method can well enhance the spatial spectrum of line spectrum units, restrain the spatial spectrum of background noise units, and improve the performance of the broadband beam-forming.
