The disclosed technology includes device, systems, techniques, and methods for mm-wave backscattering and energy harvesting systems utilizing a Rotman-Lens-based rectenna system. An mm-wave backscattering and energy harvesting system can include one or more antenna, a Rotman Lens having a beam port side and an antenna side in electrical communication with the one or more antenna, and a switching network in electrical communication with the beam port side of the Rotman Lens. The switching network can be configured to cause the system to operate in either a backscattering mode or an energy harvesting mode.

A wireless-power harvester integrated in a small device, comprising a stamped metal harvesting antenna. The stamped metal antenna is formed into a meandering shape. A first end of the meandering shape is a free end positioned within free space of a housing of a small device, and a second end of the meandering shape is coupled to a PCB that includes electrical components for operating and powering the small device. The PCB is configured to operate as a ground plane for the stamped metal antenna. An intermediate portion, disposed between the first end and the second end of the meandering shape, is coupled to power-conversion circuitry that is separate from the PCB. The power-conversion circuitry is configured to convert the one or more RF power waves harvested by the stamped metal harvesting antenna into usable energy for charging a battery of the small device or for powering the small device.

The disclosure relates to a pre-5.sup.th-Generation (5G) or 5G communication system to be provided for supporting higher data rates Beyond 4.sup.th-Generation (4G) communication system such as Long Term Evolution (LTE). According to embodiments of the disclosure, an antenna module in a wireless communication system may include: a plurality of antenna elements; a first antenna substrate; a second antenna substrate; and a Printed Circuit Board (PCB). A first side of the first antenna substrate may be coupled to each of the plurality of antenna elements, and a second side of the first antenna substrate opposite to the first side of the first antenna substrate may be coupled to the PCB. A first side of the second antenna substrate may be coupled to each of the plurality of antenna elements, and a second side of the second antenna substrate opposite to the first side of the second antenna substrate may be coupled to the PCB. A face between the first side of the first antenna substrate and the second side of the first antenna substrate may face a face between the first side of the second antenna substrate and the second side of the second antenna substrate.

A passive wireless sensor system is disclosed that includes components fabricated from carbon nanotube (CNT) structures. In some situations, the passive wireless sensor system includes a CNT structure sensor and an antenna that communicates wirelessly by altering an impedance of the antenna. The passive wireless sensor system includes a non-battery-powered energy storage device that harvests energy from carrier signals received at the antenna. The antenna and the energy storage device can be formed from CNT structures.

A multi-mode wireless power receiving device and method are disclosed. The multi-mode wireless power receiving device can comprise: an antenna module comprising an outer loop and an inner loop; a mode control unit for controlling an operation mode of the antenna module; a switch connecting the outer loop and the inner loop, and operated by the mode control unit; an outer loop module for supporting a magnetic resonance method and NFC communication by using the outer loop, according to the operation of the switch; and an inner loop module using the outer loop and the inner loop simultaneously so as to support a magnetic induction method according to the operation of the switch, thereby transmitting power.

According to one embodiment, a communication device is described comprising an antenna, a signal path for supplying a signal to the antenna, two directional couplers arranged within the signal path, wherein each directional coupler is coupled to an adjustable impedance defining the characteristic impedance of the directional coupler, a controller configured to set, for each of a plurality of impedances, the adjustable impedances of the directional couplers to the impedance, a return loss measurement circuit configured to determine, for each of the plurality of impedances, a return loss of the signal path when the adjustable impedances of the directional couplers are set to the impedance and a load impedance determination circuit configured to determine a load impedance of the signal path based on the determined return losses.

Disclosed herein is an antenna apparatus for use in harvesting ambient radio frequency, RF, energy. The apparatus comprises one or more RF antenna components arranged to receive RF energy for producing electricity. The one or more RF antenna components comprise a plurality of frequency filtering components, each frequency filtering component being arranged to filter a respective frequency band of the received RF energy. Also disclosed herein is an apparatus comprising a rectifying circuit arranged to convert a variable electrical signal received at an input from an associated antenna into a direct current electrical signal for supplying to an electrical energy storage unit, the antenna for use in harvesting ambient radio frequency, RF, energy. The apparatus also comprises a power management module having an input arranged to receive the direct current and control supply of the direct current to the electrical energy storage unit. The rectifying circuit comprises a plurality of transmission lines, wherein the input of the rectifying circuit and the input of the power management module are connected via the plurality of transmission lines. The power management module is arranged at least partially within a boundary defined by the plurality of transmission lines.

A rectenna includes an antenna configured to receive a radio wave, a rectifier circuit configured to rectify the radio wave received by the antenna, a transmission line connected to the antenna and the rectifier circuit, and a modulation input circuit including a variable capacitance element. The variable capacitance element is connected at one end to a portion of the transmission line between an antenna connecting portion at which the antenna is connected to the transmission line and a rectifier circuit connecting portion at which the rectifier circuit is connected to the transmission line, and is configured such that the capacitance thereof varies in accordance with the voltage of a modulated signal wave input to the other end of the variable capacitance element.

An energy harvesting device includes: a substrate; a plurality of split-ring resonators (SRRs) on the substrate configured to generate a voltage based on receiving incident light waves; and a transmission line electrically coupled to the plurality of SRRs, the transmission line being configured to transmit the generated voltage to an external system.

Circuits and methods concerning radio frequency (RF) communication are disclosed. In some example embodiments, an apparatus includes a first antenna providing a signal path, having at least one loop, between a first pair of nodes. The apparatus also includes a second antenna providing a signal path, having one or more loops, between a second pair of nodes. The second antenna is placed sufficiently close to the first antenna to cause the second antenna to resonate in response to an RF signal being applied to the first pair of nodes by a communication circuit.