China's Smart Surface Research Explores Turning Radar Waves Into Power for Stealth Aircraft

A radar beam could become an energy source

Researchers at Xidian University in China are exploring an electromagnetic surface that could capture incoming radar energy and turn part of it into usable electricity. The proposal connects two ambitions: helping aircraft manage the signals that reveal their position and developing wireless networks that combine communication, sensing and power transfer.

As of December 30, 2025, the work describes a theoretical and experimental framework, rather than a deployed weapon system. Its most striking military possibility is a stealth aircraft drawing energy from the radar beam tracking it. The immediate prospect is modest amounts of electricity for equipment that needs little power. Running a jet engine solely on radar energy remains science fiction for now.

The technology at the centre of the work is a reconfigurable intelligent surface, known as RIS. This is a programmable surface containing hundreds or thousands of tiny elements that change how incoming electromagnetic waves are reflected or absorbed. Current prototypes demonstrate beam steering of up to plus or minus 45 degrees, with low side lobes, meaning relatively little energy is directed away from the intended beam.

The same ability to control waves could help future 6G networks reach places where buildings or terrain block a direct signal. It could also support sensors that collect energy from nearby transmissions, reduce unwanted interference and make some wireless links harder to intercept.

The research brings these possibilities together in a system intended to sustain its own operation by combining wireless information transfer with energy harvesting. Its practical value will depend on how much energy reaches the surface, how efficiently that energy can be converted and whether the hardware can survive the conditions in which it would operate.

How programmable surfaces change stealth

Military aircraft have long used their shape and special materials to reduce the radar signals returning to an enemy receiver. A radar sends out radio waves and looks for their reflections. A smaller return makes an aircraft harder to detect or track.

Traditional stealth designs address that problem partly through the shape of the aircraft body, which scatters incoming waves, and partly through coatings that absorb them. Those materials generally have properties fixed during manufacturing. The Xidian proposal adds a surface whose response can change while it operates.

An RIS can adjust properties such as phase and amplitude. In simple terms, phase describes where a wave is in its repeating cycle, while amplitude describes its strength. Changing those properties across many small elements allows the surface to influence the direction and strength of the resulting signal.

The researchers describe this architecture as inexpensive and highly programmable. Unlike a conventional antenna that needs substantial power and hardware to generate signals, an RIS mainly changes signals already present in its surroundings.

For stealth applications, the proposed advance is to make some absorbed energy useful. Instead of simply scattering a radar wave or absorbing it without recovering electricity, a surface would direct part of that energy into a harvesting circuit. The concept could allow an aircraft to use energy from a hostile transmission for onboard equipment while controlling how the remaining wave behaves.

Using one signal for information and electricity

The team describes its approach as RIS assisted simultaneous information and power transfer. The phrase means that one electromagnetic signal serves two purposes: carrying information and supplying energy.

In the proposed model, the surface captures an incoming signal and sends part of its energy to an internal harvesting circuit. The rest is manipulated for communication or other forms of signal control. Radar beams, satellite links and communication transmissions could therefore become resources as well as potential sources of interference or detection.

The paper describes this process as passive: the surface itself does not emit detectable signals. That feature matters for platforms seeking to remain hidden from electronic support measures, the systems used to detect and monitor electromagnetic transmissions.

Collecting energy from radar or other surrounding signals could allow the surface to operate without traditional batteries. The amount of useful power would still depend on the incoming transmission and the equipment being supplied. A surface sustaining its own control electronics has a different energy requirement from an aircraft powering its onboard systems.

Could aircraft cooperate to reduce detection?

The researchers extend the idea beyond a single aircraft through a concept they call electromagnetic cooperative stealth. Multiple connected platforms would share information and adjust their RIS coatings together to reduce their combined radar cross section, a measure of how visible an object is to radar.

A formation of drones or aircraft could theoretically coordinate its response to incoming signals, creating blind spots or confusing tracking systems more effectively than individual platforms acting alone. The aim is collective control of visibility across the radio frequency spectrum.

The research team describes case studies combining several tasks: directing transmitted signals, choosing robot paths, adjusting the surface elements, sensing targets and gathering data. Its paper sets out the approach in these words:

In the case studies, by jointly optimizing parameters such as transceiver beamforming, robot trajectories, and RIS coefficients, solutions based on multi-agent deep reinforcement learning and multi-objective optimization are proposed to solve problems such as beamforming design, path planning, target sensing, and data aggregation

Beamforming means shaping a signal so that more of its energy travels in a chosen direction. In this context, multi-agent deep reinforcement learning involves several software agents learning how to coordinate their decisions. Multi-objective optimization seeks a workable balance between several goals, such as maintaining a communication link while adjusting movement and sensing.

The longer term vision is an integrated sensing system that adapts to its surroundings. Connected platforms would respond to the particular electromagnetic threats they encounter, changing their behaviour as conditions change.

Why the same work matters for 6G

Future civilian wireless networks face a related problem: signals do not always travel where users need them. Buildings, mountains and other obstacles can block a direct path, leaving gaps in coverage. An intelligent surface could redirect an existing signal toward a receiver beyond that obstruction.

The prototypes' steering range of plus or minus 45 degrees illustrates this ability to change a beam's direction. Keeping side lobes low helps concentrate the redirected energy where it is wanted, rather than sending as much into unintended directions.

RIS research reflects a wider approach to 6G development in which progress comes from changing the environment through which signals travel, as well as improving the chips inside devices. A programmable surface could make part of that environment responsive to network needs.

The researchers envisage integrated sensing and power supply for satellites or base stations. Their hardware concept combines data transmission with functionality resembling radar, seeking to use spectrum and equipment more efficiently. The same platform would help carry information, detect objects or conditions, and collect energy.

By controlling both scattered electromagnetic waves and actively radiated signals, the system aims to reduce the space and hardware normally needed for several separate functions. One possible result is smaller base stations that are easier to install and use less energy than current cellular towers.

Supporters of 6G technology also envisage holograms, digital twins and extensive Internet of Things networks. Digital twins are digital representations of physical objects or systems, while the Internet of Things connects devices such as sensors. Intelligent surfaces could help some of those devices collect small but useful amounts of energy from surrounding transmissions, extending battery life or allowing sensors to power themselves.

Controlling where signals can travel

RIS technology could also shape wireless access by creating intentional radio dead zones. A surface configured to reduce signals in a chosen area could help manage interference and limit opportunities for electronic eavesdropping.

For a secure facility, the proposed applications include reducing the escape of signals carrying information and limiting unwanted signals entering from outside. Here, controlling the path of a wave serves a security purpose rather than simply improving coverage.

Previous research cited in the study also examines RIS for resisting jamming, maintaining communication with unmanned aerial vehicles and radio surveillance. These tasks involve changing conditions and competing demands that older optimization tools often struggle to handle.

The European Space Agency has highlighted RIS as a candidate for communication between satellites and the ground. Controllable reflection and redirection could help route connections around physical obstacles, including mountains and tall buildings.

Researchers from Fudan University, the University of Sydney and the Commonwealth Scientific and Industrial Research Organization have also described the potential to combine RIS with artificial intelligence to improve the security of Internet of Things connections between airborne platforms and the ground. Those applications connect the military interest in managing electromagnetic exposure with the needs of connected devices in future smart cities.

The available power sets the limits

Harvested power is currently modest. The original military vision includes using captured radar energy for propulsion, sensors or communication systems, but the practical near term possibilities described are equipment requiring little electricity, such as some avionics, sensors or communication buffers.

Energy conversion efficiency depends heavily on the frequency and intensity of the incoming signal. A surface needs both a suitable transmission to capture and a circuit capable of turning enough of that energy into useful electrical power.

Higher frequency signals envisaged for 6G can carry more concentrated energy, while existing radar systems operate across different frequency bands. Those bands may be poorly suited to a particular harvesting design. A surface intended to collect energy from one kind of transmission therefore faces different demands when exposed to another.

The researchers frame the idea of radar illumination becoming counterproductive for the radar operator as a conceptual shift rather than an immediate operational reality. Under that concept, a transmission intended to locate an aircraft could also supply the aircraft with some electricity.

The central engineering task is to make that contribution useful while preserving the surface's other functions. Energy collection, communication and control of reflected signals all depend on how the incoming wave is handled.

What must change before aircraft deployment?

Fast aircraft and missiles present challenges beyond those faced by a surface installed in a fixed location. Integrating programmable elements, harvesting circuits and control electronics into their exterior would require hardware able to withstand strong aerodynamic forces and changing temperatures.

Materials science, durability and control electronics remain major areas of work. A useful system would also have to function in a complex electromagnetic environment containing transmissions with different frequencies, strengths and directions.

Coordinated operation adds another layer of difficulty. The cooperative stealth concept requires platforms to share data and adjust their surfaces as they move. The research's proposed learning and optimization methods address that need to make several decisions together.

The framework has yet to become an operational military system, and no deployment date is given. Its practical prospects depend on further progress in energy conversion, resilient materials and the integration of the technology with moving platforms.

A shared platform in the competition over 6G

China's work takes place during competition with the United States over future wireless infrastructure and 6G standards. Both countries are pursuing advanced communications and data centres in space that could support artificial intelligence and future connectivity.

China's position in RIS research could support networks that adjust how signals travel, particularly where direct paths are blocked and conventional 5G coverage is difficult. The same underlying control of electromagnetic waves is what makes the technology relevant to stealth, sensing and communications.

Combining those functions in one hardware platform could reduce equipment requirements while addressing interference and eavesdropping. The attraction is a surface that performs several jobs using the electromagnetic signals around it.

The research therefore links two distinct ambitions: collecting useful energy while managing radar exposure, and building wireless infrastructure that can redirect signals and support connected devices with lower power needs. Progress toward either depends on turning the proposed framework into durable, efficient hardware.

The Bottom Line

• Xidian University researchers are exploring programmable surfaces that convert part of incoming radar or other radio signals into electricity.
• The work combines communication, energy harvesting and control of electromagnetic waves in a theoretical and experimental framework.
• Current prototypes demonstrate beam steering up to plus or minus 45 degrees with low side lobes.
• Cooperative stealth would involve connected aircraft or drones sharing data and adjusting their surfaces together.
• Civilian possibilities include better coverage around obstacles, integrated sensing, smaller base stations and sensors that collect power from surrounding transmissions.
• Security applications include managing interference, resisting jamming and creating intentional radio dead zones.
• Available power remains modest. Aircraft integration requires further work on conversion efficiency, materials, electronics and durability, with no deployment date given.