Researchers at Southeast University in China have developed a reprogrammable metasurface that processes radio-frequency signals directly within electromagnetic waves, bypassing the need to convert signals into digital data for standard computing processors, according to a study published in Nature Communications.
How Electromagnetic-Space Computers Process Radio Waves Directly
Traditional radio communication relies on converting electromagnetic waves into electrical signals and digitizing them into numbers for processing. According to electrical engineers Jun Yan Dai, Qiang Cheng, and Tie Jun Cui, the study’s corresponding authors, the new system acts as a reprogrammable electromagnetic-space computer. Signals are processed directly during wave propagation without requiring conversion into digital data for conventional processors, the researchers told ScienceAlert.
Radio waves occupy the low-frequency end of the electromagnetic spectrum and have a set of properties that make them especially useful for transmitting information. These waves can propagate over great atmospheric distances, bend around barriers, penetrate select materials, and many maintain functionality during atmospheric conditions that disrupt shorter wavelengths. We use them for all sorts of technology, from Wi-Fi to radar to GPS to broadcast media. However, applications like radar require precise manipulation of wave direction, phase, and amplitude.
Did you know? Metasurfaces are thin, engineered surfaces covered in tiny structures designed to alter electromagnetic waves in carefully controlled ways. The Southeast University team’s surface allows researchers to change how incoming radio waves are manipulated over both space and time.
Controlling Fourier Transforms and Convolutions Without New Hardware
The Southeast University team’s architecture builds upon the long-term development of time-coding metasurfaces. In 2018, the group introduced the concept of time-domain digital coding metasurfaces, extending control from the static spatial domain into the time domain. By establishing a direct relationship between time-coding sequences and mathematical operations, the metasurface uses electromagnetic waves as a computational medium, according to the researchers.
The system performs two fundamental signal-processing operations: Fourier transforms, which break a pattern into its constituent parts to reveal Doppler shifts and object speed, and convolutions, which locate where a known pattern occurs to determine distance. Rather than building two separate physical systems, the team created a single metasurface that alternates between tasks by switching its time-coding sequence.
- Fourier Transforms: Breaks patterns apart, revealing Doppler shifts to calculate how fast an object moves.
- Convolutions: Matches reflected pulses with transmitted signals to determine object distance.
- Dynamic Switching: Alters the time-coding sequence to change computational tasks without modifying hardware.
Lab Testing and Real-World Radar Performance
The researchers tested the metasurface in a clean laboratory setting as well as outdoors under realistic multipath and clutter conditions. The system accurately performed both operations in real-time. With 500 sampling points, the system calculated a velocity of 201 meters per second upon receiving a simulated radar echo from a target traveling at 200 meters (656 feet) per second, and reached 199.5 meters per second using 1,000 sampling points—with both measurements staying inside the resolution limits of the platform.
Testing distance measurement with simulated targets ranging from 4 to 28 kilometers (2.5 to 17.5 miles) away yielded errors that remained within the system’s 300-meter resolution. Conventional electronics are still required to generate and load time-coding sequences, drive and synchronize the metasurface, and receive the output. However, this approach simplifies the signal-processing chain and reduces reliance on high-speed analog-to-digital converters and digital processors.
The next hurdle for this technology is increasing modulation speed to handle wider-band signals while managing potential signal losses and hardware complexity.
Frequently Asked Questions
What is an electromagnetic-space computer?
It is a system that processes signals directly within electromagnetic waves as they interact with a programmable surface, removing the need to convert entire signals into digital data for conventional processors, according to the study’s authors.
What are the primary mathematical operations performed by the metasurface?
The metasurface performs Fourier transforms to analyze velocity via Doppler shifts and convolutions to determine target distance, switching between tasks by altering its time-coding sequence.
Where might this technology be applied in the future?
Researchers envision applications in radar, 6G communications, satellite systems, and automotive radar, utilizing a single hardware platform that switches flexibly between computational tasks.
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