Theoretical study of vector-vortex field generated by quasi-periodic planar structure

This study presents a rigorous analysis of the vector-vortex field generated by quasi-periodic planar structure (qpps) based on the vectorial Huygens's principle. This letter focuses on the longitudinal component of electrical fields arising from the qpps. We show theoretically that such component is comparable to transverse components in the near field of qpps. Moreover, we demonstrate that the longitude field is also of vortex, with different topological charge from that by transverse components. Selected results are presented to verify the derived theory. ? 2014 IEEE.EI

Machine-learning reprogrammable metasurface imager

Conventional imagers require time-consuming data acquisition, or complicated reconstruction algorithms for data post-processing. Here, the authors demonstrate a real-time digital-metasurface imager that can be trained in-situ to show high accuracy image coding and recognition for various image sets

Microwave Speech Recognizer Empowered by a Programmable Metasurface

International audienceSpeech recognition becomes increasingly important in the modern society, especially for human–machine interactions, but its deployment is still severely thwarted by the struggle of machines to recognize voiced commands in challenging real‐life settings: oftentimes, ambient noise drowns the acoustic sound signals, and walls, face masks or other obstacles hide the mouth motion from optical sensors. To address these formidable challenges, an experimental prototype of a microwave speech recognizer empowered by programmable metasurface is presented here that can remotely recognize human voice commands and speaker identities even in noisy environments and if the speaker's mouth is hidden behind a wall or face mask. The programmable metasurface is the pivotal hardware ingredient of the system because its large aperture and huge number of degrees of freedom allows the system to perform a complex sequence of sensing tasks, orchestrated by artificial‐intelligence tools. Relying solely on microwave data, the system avoids visual privacy infringements. The developed microwave speech recognizer can enable privacy‐respecting voice‐commanded human–machine interactions is experimentally demonstrated in many important but to‐date inaccessible application scenarios. The presented strategy will unlock new possibilities and have expectations for future smart homes, ambient‐assisted health monitoring, as well as intelligent surveillance and security

Microwave Speech Recognizer Empowered by a Programmable Metasurface

We present an experimental prototype of a microwave speech recognizer empowered by a programmable metasurface that can recognize voice commands and speaker identities remotely even in noisy environments and if the speaker’s mouth is hidden behind a wall or face mask. Thereby, we enable voice-commanded human machine interactions in many important but to-date inaccessible application scenarios, including smart health careand factory scenarios. The programmable metasurface is the pivotal hardware ingredient of our system because its large aperture and huge number of degrees of freedom allows our system to perform a complex sequence of tasks, orchestrated by artificial-intelligence tools. First, the speaker’s mouth is localized by imaging the scene and identifying the region of interest. Second, microwaves are efficiently focused on the speaker’s mouth toencode information about the vocalized speech in reflected microwave biosignals. The efficient focusing on the speaker’s mouth is the origin of our system’s robustness to various types of parasitic motion. Third, a dedicated neural network directly retrieves the sought-after speech information from the measured microwave biosignals. Relying solely on microwave data, our system avoids visual privacy infringements. We expect that thepresented strategy will unlock new possibilities for future smart homes, ambient-assisted health monitoring and care, smart factories, as well as intelligent surveillance and security