Examples disclosed herein relate to a meta-structure based active reflectarray for passive and active reflection. A control module is coupled to reflection elements to provide energy and change the phase of the elements.

Certain aspects of the present disclosure provide techniques for user equipment (UE) positioning using one or more intelligent reflecting surfaces (IRSs). A method that may be performed by a UE includes for each IRS of the one or more IRSs: identifying a first IRS reflection center, measuring a first impulse response from the IRS to obtain a first measured impulse response representation, determining a first impulse response for a first ray reflected from the first IRS reflection center of the IRS, estimating a first position of the UE based on, at least, the first IRS reflection centers for each of the one or more IRSs and the first impulse responses for each of the one or more IRSs, and estimating a second position of the UE in an iterative manner until one or more conditions are satisfied.

A system and methods by which a reconfigurable intelligent surface device is dynamically configured to control the reflection of transmissions made between an access point and one or more client devices so as to protect the transmissions from being properly received by an unauthorized device. These methods may be used to maintain data confidentiality, particular for remote workers. The positions of the access point and client devices are used to configure the reconfigurable intelligent surface device to reflect the transmissions inward and avoid/minimize leakage outside a physical space.

Large intelligent surfaces (LISs) with sparse channel sensors are provided. Embodiments described herein provide efficient solutions for these problems by leveraging tools from compressive sensing and deep learning. Consequently, an LIS architecture based on sparse channel sensors is provided where all LIS elements are passive reconfigurable elements except for a few elements that are active (e.g., connected to baseband). Two solutions are developed that design LIS reflection matrices with negligible training overhead. First, compressive sensing tools are leveraged to construct channels at all the LIS elements from the channels seen only at the active elements. These full channels can then be used to design the LIS reflection matrices with no training overhead. Second, a deep learning-based solution is deployed where the LIS learns how to optimally interact with the incident signal given the channels at the active elements, which represent the current state of the environment and transmitter/receiver locations.

A method of manufacturing an electromagnetic wave reflecting structure includes the steps of presetting an operating frequency, a reflected wave pointing angle, an incident wave pointing angle, and an incident distance of an electromagnetic wave; obtaining an electromagnetic wave reflecting structure phase distribution of an electromagnetic wave reflecting structure according to the operating frequency, the reflected wave pointing angle, the incident wave pointing angle, and the incident distance; and arranging a plurality of reflecting elements on a substrate according to the electromagnetic wave reflecting structure phase distribution and a reflecting element phase curve of any one of the reflecting elements at the operating frequency.

The disclosed embodiments relate to the design of a system that implements a reflectarray antenna. The system includes a time-modulated metasurface, which is configured to act as a planar reflector for an electromagnetic wave that is radiated by a feeder into free space at an operation frequency f.sub.0. The time-modulated metasurface includes time-modulated unit-cells that provide a nonlinear conversion between f.sub.0 and another desired frequency f.sub.d. The system also includes a phase-delay mechanism, which adjusts a phase delay by acting on a phase applied to a modulation frequency f.sub.m that modulates each unit-cell. The nonlinear conversion and the phase-delay mechanism operate collectively to facilitate angle-independent nonreciprocity by imposing different phase gradients during up-conversion and down-conversion processes, and by preventing generation of certain propagative harmonics due to total internal reflection.

A repeater device comprises a periodic array of alternating metallic phase shifting elements, the array being periodic in at least one axis, formed on a first surface of a dielectric substrate, with an opposite surface of the dielectric substrate having a ground plane formed thereon, wherein each phase shifting element provides from 0° to 360° phase shifting in the microwave frequency range. The repeater device can be utilized in a microwave network.

Apparatus comprising at least one movable reflective surface configured to reflect electromagnetic waves and at least one actuator coupled with the at least one movable reflective surface, wherein said at least one actuator is configured to at least temporarily drive a movement of said at least one reflective surface.

A design method for an intelligent reflecting surface (IRS) aided terahertz secure communication system is provided. The IRS aided terahertz multi-input single-output (MISO) system includes a base station (BS) equipped with N.sub.BS antennas, an IRS equipped with N.sub.IRS reflecting elements, a single-antenna user and a single-antenna eavesdropper. The BS transmits signals by the active hybrid beamforming to the relay of the IRS, and the IRS adjusts the signals and reflects the signals to the mobile user, which suppresses the received signal of the eavesdropper. The present invention maximizes the downlink secrecy rate by establishing a joint optimization function and maximizes the system data transmission rate by a cross-entropy based search method.

In some example embodiments, there may be provided an apparatus. The apparatus may include a surface including at least one electro-magnetic reflective element programmed to provide a plurality of reflected signals, such that the plurality of reflected signals constructively adds at a location of a receiver of the plurality of reflected signals. Related systems, methods, and articles of manufacture are also described.