Absorbing layers, which are crucial in applications ranging from energy harvesting to stealth technology, have been at the forefront of several technological breakthroughs in recent years. These absorbers efficiently capture electromagnetic waves over wide frequency ranges, making them indispensable in fields such as communication systems, remote sensors, and the Internet of Things (IoT). These technologies play a critical role in advancing our capabilities in self-powered devices, stealth applications, and robust communication networks, driving innovation in industries worldwide.
In the realm of energy harvesting, absorbers are used to capture and convert ambient electromagnetic energy into usable power. This capability is essential for remote sensors and IoT systems, which require energy efficiency and long-term sustainability without relying on traditional power sources like batteries. The ability of absorbers to operate across various frequency ranges also paves the way for the development of self-sustaining technologies that power critical infrastructure in fields like environmental monitoring and healthcare systems.
Beyond energy harvesting, absorbing layers are also integral to stealth technology. In military and defense applications, these layers help minimize radar visibility, enhancing the performance and survivability of aircraft, drones, and naval systems. By absorbing radar waves, rather than reflecting them, these absorbers reduce the risk of detection, which is a crucial factor in modern warfare. Similarly, in communication systems, these layers reduce electromagnetic interference (EMI) and help to optimize the signal-to-noise ratio, improving the quality of signals while ensuring that devices and systems work more efficiently in crowded electromagnetic environments.
Despite these impressive applications, the ongoing development of absorbers faces a significant challenge: achieving greater functionality and broader bandwidths, all while maintaining compactness and lightweight designs. To keep pace with the demand for ultra-thin absorbing layers with higher bandwidths, researchers and engineers must overcome the limitations imposed by existing technologies.
The primary challenge in designing advanced absorbing layers lies in their bandwidth-to-thickness ratio. Essentially, this ratio determines how effectively an absorber can capture electromagnetic waves over a wide range of frequencies while remaining thin and lightweight. Current absorbers, regardless of their material composition or operational frequency range, significantly underperform in this regard. Their bandwidth-to-thickness ratio fails to meet the theoretical upper bound, limiting their potential in a variety of applications.
Breaking Through the Bandwidth-To-Thickness Barrier
A new study published in Nature Communications by Professor Younes Ra’di and his research team from the Department of Electrical Engineering and Computer Science represents a breakthrough in addressing this limitation. In their research, the team introduces a novel concept for designing ultra-thin absorbers that can achieve a record-breaking bandwidth-to-thickness ratio. This ratio could be several times greater than what is currently achievable with traditional absorbing layer designs.
According to Professor Ra’di, existing designs have failed to fully exploit the theoretical potential of passive, linear, and time-invariant absorbing systems. These systems, which do not require external power sources or active components, are critical for use in a wide range of technologies, from defense applications to energy harvesting devices. By pushing the boundaries of these systems, the researchers have developed a way to design absorbers that come close to the theoretical upper limit of bandwidth-to-thickness, marking a major step forward in the field.
The key innovation introduced in this study is a new approach to absorber design that redefines how electromagnetic waves are captured and distributed within the material. Rather than relying on conventional techniques that restrict the bandwidth-to-thickness ratio, the researchers’ method allows for a more efficient distribution of energy across a broader range of frequencies, without increasing the physical thickness of the absorber.
Achieving Record-Breaking Performance
To test the viability of their new concept, the research team designed an absorber that demonstrated an unprecedented performance in terms of its bandwidth-to-thickness ratio. The design was experimentally verified, with results showing that the absorber could capture electromagnetic waves across a wider frequency range while maintaining an ultra-thin profile. This achievement not only confirms the validity of their theoretical predictions but also sets a new standard for the design of advanced electromagnetic absorbers.
“Our findings have the potential to make significant contributions to various industries, including defense, energy harvesting, and advanced communication systems, by addressing critical challenges in electromagnetic absorption technology,” says Ra’di. “These innovations pave the way for a new generation of absorbers that can be integrated into technologies requiring high-performance electromagnetic control, without compromising on size, efficiency, or cost.”
This work represents a pivotal moment for industries relying on electromagnetic absorbers to enhance the capabilities of their systems. In the defense sector, for instance, the development of more efficient absorbers could lead to stealthier military equipment, better radar-absorbing materials, and more effective countermeasures against enemy detection. In communication networks, these absorbers could help improve signal clarity and reduce the risk of interference, particularly in crowded environments where devices are competing for the same frequency bands. For energy harvesting, ultra-thin absorbers could help power a wide range of remote sensors and IoT devices, creating more efficient and sustainable solutions.
Looking Ahead: The Future of Electromagnetic Absorption Technology
Professor Ra’di and his team’s groundbreaking work has already begun to attract significant attention from both the scientific community and industries seeking to leverage this new absorber technology. In addition to its potential impact on defense, energy harvesting, and communication systems, this innovation could also find applications in fields such as automotive engineering, smart cities, and space exploration. As the demand for more compact, efficient, and high-performance technologies continues to rise, the role of ultra-thin absorbers will become increasingly important.
Looking to the future, there is great potential for further research and development in this area. The team’s work opens up exciting possibilities for designing next-generation electromagnetic materials that can be seamlessly integrated into a wide range of applications. With the ongoing advancement of nanotechnology and materials science, it is likely that we will see even thinner, more efficient absorbers that push the limits of electromagnetic wave manipulation even further.
Moreover, the ability to design absorbers that perform exceptionally well over a wide range of frequencies while maintaining a compact footprint is poised to drive the development of next-generation devices and technologies. From wearable electronics to autonomous vehicles, absorbers with ultra-high bandwidth-to-thickness ratios could play a pivotal role in making these devices more efficient, reliable, and sustainable.
Conclusion
The new absorber design introduced by Professor Younes Ra’di and his team represents a significant leap forward in electromagnetic absorption technology. By achieving a record-high bandwidth-to-thickness ratio, their approach addresses critical challenges in defense, energy, and communication technologies, enabling more efficient, powerful, and compact systems. As industries continue to demand smaller, more functional components, the impact of these innovations will be far-reaching, potentially transforming fields ranging from military defense to smart technology. With continued research and development, this breakthrough could lead to even greater advancements in electromagnetic wave management, shaping the future of technology in profound ways.
Reference: Pardha S. Nayani et al, Passive highly dispersive matching network enabling broadband electromagnetic absorption, Nature Communications (2025). DOI: 10.1038/s41467-025-56167-4