Urban Walls to Speak the Language of Metasurfaces: Scientists Develop a Way to Boost Radio Signals
Reliable communication in urban environments is a real challenge. Radio signals must pass through obstacles like walls, buildings, and other structures, which causes them to scatter and reduces their capacity. A team of researchers from the Johns Hopkins Applied Physics Laboratory (APL) has developed a technology that could revolutionize data transmission in areas with a high concentration of devices.
The researchers have brought to life the concept of metasurfaces—special structures capable of reflecting, redirecting, and modulating electromagnetic signals to enhance bandwidth. Previously, the use of such surfaces was limited by material drawbacks: signal losses and the need for resonant components in their design. The APL team’s technology overcomes these limitations and strengthens reflective properties.
“This development will find applications in advanced communications, new low-power sensors, and operations in the most challenging environments,” emphasized Jeff Maranchi, head of the research program.
How the Technology Works
The key feature of these designs is the ability to independently control both the amplitude (strength) and phase (timing) of an electromagnetic wave.
“When a signal passes through a metasurface, it interacts with each of the layers at both the input and output. These interactions are very complex. Each layer essentially ‘communicates’ with the others—they all seem to know about each other. The layers interact to create the desired effect,” explained Tim Sleasman, lead author of the study.
The signal control system consists of a set of patch-like elements, tuning knobs, varicap diodes, and resistors. The dynamic cascaded metasurface balances amplitude and phase—all on a small, inexpensive printed circuit board.
This new design solves the problem of uneven radio wave loss typical of classic structures and incorporates several resonant materials.
Beyond Telecommunications
The invention’s potential goes far beyond just telecommunications. “While our work focused on radio frequency applications, the concepts and methods we’ve presented are valuable across a wide range of the electromagnetic spectrum,” said David Shrekenhamer, program manager for physics, electronic materials, and devices at APL.
For example, the technology could help create more compact and lightweight sensors that use minimal energy. Sleasman gave an example: “You might have a sensor on a buoy in the ocean measuring water salinity. You don’t want to load it with batteries or require it to actively transmit data. With one of these surfaces, you could fly over the object in a helicopter and retrieve the data by pinging the metasurface, which would reflect the signal back.”
“We’re excited to see how much interest this technology is generating in both the commercial sector and government agencies,” Sleasman said. “We plan to continue developing the concept for various applications.”