Programmable metasurfaces have great potential for the implementation of low-complexity and low-cost phased arrays.Due to the difficulty of multiple-bit phase control,conventional programmable metasurfaces suffer a re...Programmable metasurfaces have great potential for the implementation of low-complexity and low-cost phased arrays.Due to the difficulty of multiple-bit phase control,conventional programmable metasurfaces suffer a relatively high sidelobe level(SLL).In this manuscript,a time modulation strategy is introduced in the 1-bit transmissive programmable metasurface for reducing the SLLs of the generated patterns.After the periodic time modulation,harmonics are generated in each reconfigurable unit and the phase of the first-order harmonic can be dynamically controlled by applying different modulation sequences onto the corresponding unit.Through the high-speed modulation of the real-time periodic coding sequences on the metasurface by the programmable bias circuit,the equivalent phase shift accuracy to each metasurface unit can be improved to 6-bit and thus the SLLs of the metasurface could be reduced remarkably.The proposed time-modulated strategy is verified both numerically and experimentally with a transmissive programmable metasurface,which obtains an aperture efficiency over 34%and reduced SLLs of about-2o dB.The proposed design could offer a novel approach of a programmable metasurface framework for radar detection and secure communication applications.展开更多
基金The authors acknowledge supports sponsored by the Shanghai Sailing Program(20YFi447000)the NWPU research fund for young scholars(G2022WD01008)+1 种基金the National NaturalScienceeFoundationofChina(61735010,61901263,and 62071291)the National Key Research and Development Program of China(2017YFA0700202).
文摘Programmable metasurfaces have great potential for the implementation of low-complexity and low-cost phased arrays.Due to the difficulty of multiple-bit phase control,conventional programmable metasurfaces suffer a relatively high sidelobe level(SLL).In this manuscript,a time modulation strategy is introduced in the 1-bit transmissive programmable metasurface for reducing the SLLs of the generated patterns.After the periodic time modulation,harmonics are generated in each reconfigurable unit and the phase of the first-order harmonic can be dynamically controlled by applying different modulation sequences onto the corresponding unit.Through the high-speed modulation of the real-time periodic coding sequences on the metasurface by the programmable bias circuit,the equivalent phase shift accuracy to each metasurface unit can be improved to 6-bit and thus the SLLs of the metasurface could be reduced remarkably.The proposed time-modulated strategy is verified both numerically and experimentally with a transmissive programmable metasurface,which obtains an aperture efficiency over 34%and reduced SLLs of about-2o dB.The proposed design could offer a novel approach of a programmable metasurface framework for radar detection and secure communication applications.
