5G technology has brought with it a series of infrastructural and design challenges. Owing to a higher frequency band than previous generations, 5G can struggle with range, especially when there are obstructions in the way.

This week, Japanese company Kyocera has announced a new transmissive metasurface technology that has the potential to improve transmissibility and range for 5G technology.

Prototype of the transparent transmissive metasurface. Image used courtesy of Kyocera

In this article, we’ll discuss the range challenges for 5G, metasurface technology, and the potential of Kyocera’s new development.

The Trouble With 5G Transmission

Compared to previous generations of wireless technology, 5G has unique difficulties when it comes to range and transmissibility. This is largely due to the fact that 5G operates in higher frequency bands than previous generations.

As defined by basic path loss equations, the higher the wave frequency, the greater the path loss (i.e., attenuation) of the signal will be. Given the same transmission power, 5G radio waves will inherently reach a shorter distance than a lower-frequency counterpart.

The path loss equation shows a directly proportional relationship between path loss and signal frequency. Image used courtesy of CAS DataLoggers

In addition, the higher frequency bands cause 5G signals to exhibit a propagation nature that is highly "rectilinear"—that is, a straight-line propagation. This poses a significant problem because there are almost always obstructions such as buildings or trees in a straight-line transmission path. These obstructions further attenuate the propagating signal.

Hence, 5G experiences a greater inherent path loss and is more likely to encounter obstruction-related losses due to its rectilinear nature. 

How Metasurfaces Extend 5G Range

One technology employed to improve 5G signal transmission is metasurfaces.

Metasurfaces are an optical technology that consists of human-engineered arrays of subwavelength-spaced optical scatterers on top of a flat surface. These arrays can act to either transmit or reflect incident light to focus and steer it, along with other forms of wave manipulation. Using nanofabrication techniques, metasurfaces today can work with millimeter waves, microwaves, and visible light.

Metamaterials can be used to selectively control waves. Image used courtesy of RIKEN and Nanowerk

In the context of 5G, reflective metasurfaces have been used as a way of manipulating and controlling the transmission path of radio waves. The idea is that reflective metasurfaces can help steer the incident 5G waves to avoid obstructions, decreasing overall attenuation and extending range.

However, one challenge with reflective metasurfaces is that they historically offer very limited resolution when steering 5G waves. Typically, reflective metasurfaces cannot control light at small enough angles to achieve a high level of directionality over the wave’s reflected direction.

Kyocera’s Transmissive Metasurface

This week Kyocera announced that it has developed a new technology that improves reflective metasurfaces.

The new technology is a transmissive metasurface that takes incident light and steers it by transmitting light—not reflecting it—into the desired direction. Kyocera claims that its transmissive metasurface can redirect incident waves at much smaller angles than previously possible, allowing for finer control of the redirected wave. 

Kyocera claims its new technology is an improvement on reflective metasurfaces. Image used courtesy of Kyocera

According to Kyocera, the new technology offers a proprietary flexible size development, where the transmissive area of the metasurface is proportional to the size of the metasurface itself. In this way, Kyocera can develop a transmissive metasurface of any size, allowing it to meet more applications and environments than other solutions.

Expanding 5G and 6G Reach

While it appears that no academic or peer-reviewed papers are available supporting and describing the technology in detail, the implications of Kyocera’s claims could be significant. A new way to direct signals and avoid obstructions can potentially improve signal range in 5G ranges and beyond.