Spatiotemporally varying media,which simultaneously modulating both in space and time,offer a versatile platform for dynamic control of electromagnetic waves.The multimode properties of such media are crucial for appl...Spatiotemporally varying media,which simultaneously modulating both in space and time,offer a versatile platform for dynamic control of electromagnetic waves.The multimode properties of such media are crucial for applications in quantum simulation,large-scale optical computing,and high-capacity communication systems.Here,we present a reconfigurable approach for applying spatiotemporal electromagnetic modulation in a substrate-integrated waveguide(SIW),enabling the resolution and engineering of multiple modes in spacetime crystals(STCs).We begin by demonstrating the diffraction of Floquet modes in a time crystal,analogous to a time grating.By superimposing spatial modulation,we impart additional momentum to these modes,allowing the Floquet modes to radiate into free space at distinct,angle-resolved directions.Furthermore,by incorporating multicolor spatiotemporal modulation,we achieve precise control over the Floquet-Bloch modes,facilitating multi-user video distribution.Our approach paves the way for the engineering of multiple Floquet-Bloch modes in STCs,offering promising prospects for quantum simulation,optical computing,and next-generation wireless communications.展开更多
An array of two substrate-integrated waveguide(SIW)periodic leaky-wave antennas(LWAs)with sum and difference beam scanning is proposed for application in target detection and tracking.The array is composed of two peri...An array of two substrate-integrated waveguide(SIW)periodic leaky-wave antennas(LWAs)with sum and difference beam scanning is proposed for application in target detection and tracking.The array is composed of two periodic LWAs with different periods,in which each LWA generates a narrow beam through the n=-1 space harmonic.Due to the two different periods for the two LWAs,two beams with two different directions can be realized,which can be combined into a sum beam when the array is fed in phase or into a difference beam when the array is fed 180?out of phase.The array integrated with 180?hybrid is designed,fabricated,and measured.Measurement results show that the sum beam can reach a gain up to 15.9 dBi and scan from-33.4?to 20.8?.In the scanning range,the direction of the null in the difference beam is consistent with the direction of the sum beam,with the lowest null depth of-40.8 dB.With the excellent performance,the antenna provides an alternative solution with low complexity and low cost for target detection and tracking.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.12574326,and 12174260)the support of the National Natural Science Foundation of China (Grant No.2023X0201-417-03)the Fund of the Shanghai Tech University (Start-up Funding)。
文摘Spatiotemporally varying media,which simultaneously modulating both in space and time,offer a versatile platform for dynamic control of electromagnetic waves.The multimode properties of such media are crucial for applications in quantum simulation,large-scale optical computing,and high-capacity communication systems.Here,we present a reconfigurable approach for applying spatiotemporal electromagnetic modulation in a substrate-integrated waveguide(SIW),enabling the resolution and engineering of multiple modes in spacetime crystals(STCs).We begin by demonstrating the diffraction of Floquet modes in a time crystal,analogous to a time grating.By superimposing spatial modulation,we impart additional momentum to these modes,allowing the Floquet modes to radiate into free space at distinct,angle-resolved directions.Furthermore,by incorporating multicolor spatiotemporal modulation,we achieve precise control over the Floquet-Bloch modes,facilitating multi-user video distribution.Our approach paves the way for the engineering of multiple Floquet-Bloch modes in STCs,offering promising prospects for quantum simulation,optical computing,and next-generation wireless communications.
基金Project supported in part by the National Natural Science Foundation of China(No.62171480)in part by the Guangdong Basic and Applied Basic Research Foundation,China(No.2020B1515020053)。
文摘An array of two substrate-integrated waveguide(SIW)periodic leaky-wave antennas(LWAs)with sum and difference beam scanning is proposed for application in target detection and tracking.The array is composed of two periodic LWAs with different periods,in which each LWA generates a narrow beam through the n=-1 space harmonic.Due to the two different periods for the two LWAs,two beams with two different directions can be realized,which can be combined into a sum beam when the array is fed in phase or into a difference beam when the array is fed 180?out of phase.The array integrated with 180?hybrid is designed,fabricated,and measured.Measurement results show that the sum beam can reach a gain up to 15.9 dBi and scan from-33.4?to 20.8?.In the scanning range,the direction of the null in the difference beam is consistent with the direction of the sum beam,with the lowest null depth of-40.8 dB.With the excellent performance,the antenna provides an alternative solution with low complexity and low cost for target detection and tracking.
