Successful Demonstration of Liquid Crystal Meta-surface Reflectors to Cover Outdoor Areas Between Buildings
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February 28, 2025
Japan Display Inc.
KDDI Corporation
KDDI Research, Inc.
Successful Demonstration of Liquid Crystal Meta-surface Reflectors to Cover Outdoor Areas Between Buildings
- Creating Portable, Low-Power Solar-Powered Solutions for Events -
Japan Display Inc. (Headquarters: Minato-ku, Tokyo; Chairman, CEO, and Director: Scott Callon; hereinafter "JDI"), KDDI Corporation (Headquarters: Chiyoda-ku, Tokyo; President and CEO: Makoto Takahashi; hereinafter "KDDI") and KDDI Research, Inc. (Headquarters: Fujimino City, Saitama Prefecture; President: Hajime Nakamura; hereinafter "KDDI Research") successfully developed a portable liquid crystal meta-surface reflector for millimeter waves (28GHz band) (hereinafter "LC Reflector") that can change the direction and range of reflected radio waves. On February 25, 2025, they successfully demonstrated the reflection of radio waves to cover outdoor areas between buildings where millimeter waves are difficult to reach (hereinafter "this demonstration"). Additionally, they confirmed that the liquid crystal reflectors can be powered by commercial solar panels and batteries, taking advantage of its low power consumption. As a result, it is expected that millimeter waves can be flexibly delivered to areas where radio waves are difficult to reach due to building obstructions or crowded events, thereby providing customers with high-speed, stable, and large-capacity communication. The three companies will continue to work on the practical application of liquid crystal reflectors.
LC Reflector Installed Outdoors
Specifications of the LC Reflector
Size
50cm × 50cm
Weight
8kg
This reflector can be turned ON/OFF and scatter patterns can be changed via smartphone.
■About This Demonstration
1．Background
High-frequency radio waves such as millimeter waves used in 5G can provide high-speed, large-capacity communication, but they are easily affected by buildings and trees due to their strong directivity.
JDI and KDDI Research have previously developed small-sized liquid crystal reflectors and conducted experiments to switch the direction of reflected radio waves in a test (*1). The challenge was to deliver radio waves to specific areas in real environments, such as corridors between buildings where radio waves are difficult to reach, by switching the direction of reflection.
2. Demonstration Overview
In this demonstration, the following were implemented:
•Development of a portable liquid crystal reflector of the sufficient size to reflect millimeter waves in the 28GHz band in real-word environments.
•Simulation of the installation position of the liquid crystal reflector and the voltage distribution applied to the liquid crystal.
•Confirmation that commercial millimeter waves can be reflected to pinpoint areas where radio waves are difficult to reach due to building obstructions using the liquid crystal reflector.
•Confirmation that the liquid crystal reflector can be powered by solar panels and batteries.
<Comparison before installation of the reflector>
As a result of this demonstration, it was confirmed that the liquid crystal reflector can flexibly create millimeter wave areas based on the flow of people and the width of corridors. Additionally, taking advantage of its low power consumption, it was confirmed that it can be powered by solar panels and batteries, making it promising for use in outdoor event venues.
3. Demonstration Period From December 21, 2024, to March 31, 2025
4. Demonstration Location Nishi-Shinjuku area, Shinjuku-ku, Tokyo
5. Roles of Each Company
KDDI／
KDDI Research
Construction of the demonstration environment, development of area expansion technology using liquid crystal reflectors, and execution of this demonstration.
JDI
Development of liquid crystal reflector technology and devices.
(Reference) ■ Efforts to Expand Millimeter Wave Areas
Millimeter waves are capable of high-speed communication, so they are often installed in places where people gather, such as train platforms, stadiums, and meeting places. However, due to their strong directivity and susceptibility to buildings and trees, many base stations need to be installed to meticulously expand the area. To solve this problem, KDDI has developed wireless relay technology that enables autonomous and continuous area formation in conjunction with millimeter wave base stations(*2).
In anticipation of the Beyond 5G/6G era, the continuous increase in traffic is expected, making the use of high-frequency bands, including millimeter waves, indispensable. We will continue to work on the effective use and expansion of millimeter wave areas.
