US-12620707-B2 - RIS element, antenna, antenna apparatus, communication apparatus, and method for controlling antenna apparatus

US12620707B2US 12620707 B2US12620707 B2US 12620707B2US-12620707-B2

Abstract

An antenna element receives a first radio wave and outputs a transmission signal, and receives a second radio wave and outputs a reception signal. A phase conversion unit applies a predetermined phase shift amount to a signal to be input and then output the signal. A switch connects the antenna element to one of the phase conversion unit and external receiver. When the first radio wave enters the antenna, the switch connects the antenna element to the phase conversion unit, and the transmission signal to which the predetermined phase shift amount has been applied is radiated from the antenna element. A third radio wave radiated from each of a plurality of RIS elements is deflected in a predetermined direction. When the second radio wave enters the antenna, the switch connects the antenna element to the external receiver, and the external receiver receives the reception signal.

Inventors

Shingo Watanabe
Masakazu Ono
Kenji WAKAFUJI
Kohei Yoshida

Assignees

NEC CORPORATION

Dates

Publication Date: 20260505
Application Date: 20240507
Priority Date: 20230529

Claims (8)

1 . A Reconfigurable Intelligent metaSurface (RIS) element comprising: a first antenna element configured to receive a first radio wave and output a transmission signal, and receive a second radio wave and output a reception signal; a first phase conversion unit configured to apply a predetermined phase shift amount to a signal to be input and then output the signal; and a first switch configured to connect the first antenna element to one of the first phase conversion unit and external receiver, wherein when the first radio wave enters the first antenna element, the first switch connects the first antenna element to the first phase conversion unit, so that the transmission signal to which the predetermined phase shift amount has been applied by the first phase conversion unit is radiated from the first antenna element as a third radio wave, and the third radio wave radiated from each of a plurality of the first antenna elements arranged in an array is deflected in a predetermined direction in accordance with the phase shift amount applied to the transmission signal in each of a plurality of the first phase conversion units respectively connected to the plurality of the first antenna elements, and when the second radio wave enters the first antenna element, the first switch connects the first antenna element to the external receiver, so that the external receiver receives the reception signal.
2 . An antenna comprising: a plurality of the RIS elements according to claim 1 arranged in an array; and a RIS element control unit configured to control operations of the plurality of the RIS elements, wherein in each of the plurality of the RIS elements, the first phase conversion unit applies the predetermined phase shift amount to the signal to be input and then outputs the signal in accordance with the control by the RIS element control unit, and the first switch connects the first antenna element to one of the first phase conversion unit and the external receiver in accordance with the control by the RIS element control unit.
3 . An antenna apparatus comprising: a radiation unit configured to radiate a transmission signal as a first radio wave; a reflection unit configured to reflect the first radio wave; the antenna according to claim 2 in which the first radio wave reflected by the reflection unit and a second radio wave received from outside enter; and an antenna control unit configured to control an operation of the antenna, wherein the RIS element control unit controls the first phase conversion unit and the first switch in accordance with the control by the antenna control unit.
4 . The antenna apparatus according to claim 3 , wherein the first phase conversion unit comprises a plurality of lines having line lengths different from each other, one end of each of the plurality of lines being connected to the first switch, and an other end of each of the plurality of lines being an open end which reflects the transmission signal, and the first switch selects a line connected to the first switch from among the plurality of lines in accordance with the control by the RIS element control unit, thereby enabling a phase shift amount applied to the transmission signal to be changed.
5 . The antenna apparatus according to claim 3 , wherein the reflection unit is configured as a reflecting plate composed of reflective elements arranged in an array, the reflective elements being RIS elements in which the first radio waves enter, each of the reflective elements comprises: a second antenna element configured to receive the first radio wave and output the transmission signal; a second phase conversion unit configured to apply a predetermined phase shift amount to the transmission signal and then output the transmission signal to the second antenna element; a terminator configured to terminate a signal to be input; and a second switch configured to connect the second antenna element to the second phase conversion unit when the first radio wave enters the antenna, and connect the second antenna element to the terminator when the second radio wave enters the antenna, and the transmission signal to which the phase shift amount has been applied by the second phase conversion unit is radiated from the second antenna element as the first radio wave deflected in a direction of the antenna.
6 . An antenna apparatus according to claim 3 , wherein the external receiver controls an amplitude and a phase of each of a plurality of the reception signals output from the plurality of the RIS elements so that a noise component of a signal obtained by multiplexing the plurality of the reception signals becomes smaller than a predetermined value.
7 . A communication apparatus comprising: the antenna apparatus according to claim 3 ; a transmitter configured to output a transmission signal; and the external receiver configured to receive a reception signal from the antenna apparatus.
8 . A method for controlling an antenna apparatus comprising: a radiation unit configured to radiate a transmission signal as a first radio wave; a reflection unit configured to reflect the first radio wave; an antenna in which the first radio wave reflected by the reflection unit and a second radio wave received from outside enter; and an antenna control unit configured to control an operation of the antenna, the antenna comprising: a plurality of Reconfigurable Intelligent metaSurface (RIS) elements arranged in an array in which the first radio wave and the second radio wave enter; and a RIS element control unit configured to control operations of the plurality of RIS elements in accordance with the control by the antenna control unit, and each of the plurality of RIS elements comprising: an antenna element configured to receive the first radio wave and output the transmission signal, and receive the second radio wave and output a reception signal; a phase conversion unit configured to apply a predetermined phase shift amount to a signal to be input and then output the signal in accordance with the control by the RIS element control unit; and a switch configured to connect the antenna element to one of the phase conversion unit and external receiver in accordance with the control by the RIS element control unit, wherein in the method: when the first radio wave enters the antenna, the antenna element is connected to the phase conversion unit by the switch of each of the plurality of RIS elements, and the transmission signal to which the predetermined phase shift amount has been applied by the phase conversion unit is radiated from the antenna element as a third radio wave; the third radio wave radiated from each of the plurality of RIS elements is deflected in a predetermined direction in accordance with the phase shift amount applied to the transmission signal by each of the plurality of RIS elements; when the second radio wave enters the antenna, the antenna element is connected to the external receiver by the switch of each of the plurality of RIS elements; and the reception signal is received by the external receiver.

Description

INCORPORATION BY REFERENCE This application is based upon and claims the benefit of priority from Japanese patent application No. 2023-87711, filed on May 29, 2023, the disclosure of which is incorporated herein in its entirety by reference. TECHNICAL FIELD The present disclosure relates to an RIS element, an antenna, an antenna apparatus, a communication apparatus, and a method for controlling an antenna apparatus. BACKGROUND ART With advancement of communication technology, various methods for transmitting and receiving radio signals have been proposed. For example, Japanese Unexamined Patent Application Publication No. 2022-117980 discloses the following as a technique for estimating a location of a user terminal. A reconfigurable intelligent surface (RIS) panel reflects a pilot signal transmitted from an access point, according to a predetermined reflection pattern. Upon receiving the reflected signal, a user terminal extracts features from the signal, and estimates a location of the user terminal, based on a database including a pair of a location and one or more features. Further, Japanese Unexamined Patent Application Publication No. 2020-136687 discloses a directional antenna for transmission in which a reflecting plate is provided near an array antenna, and proposes an antenna in which a reflecting plate is configured as an RIS reflecting plate. Japanese Patent Application Publication No. 2021-517406 proposes a method for transmitting and receiving radio signals to and from a radio apparatus located inside a structure having a physical barrier, such as a wall or a window, through the physical barrier. SUMMARY Recently, beamforming of a 5th-generation (5G) base station is achieved by, for example, a configuration using a solid state power amplifier (SSPA) and a phased array antenna. However, as the communication frequency becomes high, it is assumed that more heat dissipation occurs during operation, due to an increase in the number of communication elements such as antennas and amplifiers, or an increase in integration of devices. As a solution to such problems, it is conceivable that an antenna may be configured by a RIS unit capable of directionally controlling a reflected wave, to thereby transmit and receive radio waves. However, when an antenna for transmission and an antenna for reception configured by the RIS units are separately provided, the size of the antenna increases, and thus there is a problem, for example, that a place where the antenna is installed is limited and that the cost increases. The present disclosure has been made in view of the above circumstances, and an example object of the present disclosure is to transmit and receive radio waves using a single antenna configured by an array of RIS elements. In a first example aspect of the present disclosure, a Reconfigurable Intelligent metaSurface (RIS) element includes: a first antenna element configured to receive a first radio wave and output a transmission signal, and receive a second radio wave and output a reception signal; a first phase conversion unit configured to apply a predetermined phase shift amount to a signal to be input and then output the signal; and a first switch configured to connect the first antenna element to one of the first phase conversion unit and external reception means, in which when the first radio wave enters the first antenna element, the first switch connects the first antenna element to the first phase conversion unit, so that the transmission signal to which the predetermined phase shift amount has been applied by the first phase conversion unit is radiated from the first antenna element as a third radio wave, and the third radio wave radiated from each of a plurality of the first antenna elements arranged in an array is deflected in a predetermined direction in accordance with the phase shift amount applied to the transmission signal in each of a plurality of the first phase conversion units respectively connected to the plurality of the first antenna elements, and when the second radio wave enters the first antenna element, the first switch connects the first antenna element to the external reception means, so that the external reception means receives the reception signal. In a second example aspect of the present disclosure, a method for controlling an antenna apparatus including: a radiation unit configured to radiate a transmission signal as a first radio wave; a reflection unit configured to reflect the first radio wave; an antenna in which the first radio wave reflected by the reflection unit and a second radio wave received from outside enter; and an antenna control unit configured to control an operation of the antenna, the antenna including: a plurality of Reconfigurable Intelligent meta Surface (RIS) elements arranged in an array in which the first radio wave and the second radio wave enter; and a RIS element control unit configured to control operations of the plurality of RIS elem