Ultra-Efficient 5G Antenna Developed At Notre Dame Performs In Army Field Tests

In the field, the United States Army relies on fifth-generation (5G) wireless networks for secure communications, equipment tracking, and real-time health monitoring. 5G networks are also essential for the coordination of unmanned aerial vehicles with broader military operations. Current 5G technologies, however, are difficult and costly to set up, transport, and operate on the move.

To support a global footprint of secure, high-data rate wireless communications, the U.S. Army must navigate a highly fractured global radio frequency spectrum landscape. This demands stocking, transporting, and installing highly redundant traditional narrow-band antenna systems covering every possible 5G band, depending upon the region of operation. Furthermore, command post interconnectivity requires significant power, cooling, and complexity. When a command post must haul around a cargo container truck’s worth of active electronics and heavy power sources just to maintain a signal, its mobility is severely limited.

Jonathan Chisum, an associate professor in the Department of Electrical Engineering at the University of Notre Dame, has spent nearly a decade researching the fundamental science of a new, low-power antenna that could change the rules of wireless connectivity. Chisum’s antenna delivers wideband 5G connectivity while consuming a fraction of the power supplied to traditional antennas, and combines the many redundant antennas from each frequency band into one wideband antenna.

“Our wideband solution is an essential building block for mobile, agile, and resilient networks, enabling the Army to deploy 5G networks globally over varied regional frequency allocations,” said Chisum, an affiliate of Notre Dame's Wireless Institute and Notre Dame Nanoscience and Technology. “Consolidating multiple dedicated antennas into one compact and wideband antenna drastically reduces cost, complexity, and weight. And because we replace expensive, power-hungry beam-scanning electronics with an optically-inspired metamaterial lens antenna, the system draws minimal power, making it a perfect fit for mobile command posts.”

Chisum’s solution is called a millimeter-wave gradient index (GRIN) lens antenna. In a conventional high-power antenna array, electronic chips must constantly adjust the timing of signals across dozens of sub-elements to steer a radio beam in a specific direction.

A GRIN lens antenna eliminates those chips entirely. Instead, it is composed of conjoined pieces of specialized material with a complex and continuously changing internal structure. As radio waves pass through the lens, the physical properties of the material naturally bend, shape, and steer the beams to the correct angles for signal emission and detection.

Chisum’s findings have allowed his research group to develop a single antenna that operates over all of the frequency bands for 5G, a feat once thought to be impossible. Replacing power-hungry chips with passive materials also greatly reduces the energy burden of operating a 5G network.

The Army took notice.
Last year, Chisum was selected to lead an Army initiative to develop and test his GRIN lens technology in the field with an agile team of industry partners. These included a manufacturer of 3D printers specialized for radio frequency and millimeter-wave applications, as well as Cheshir Industries, a defense technology startup co-founded by Chisum alongside two of his former Notre Dame doctoral students, Nicolas Garcia (’22 Ph.D.) and Nicholas Estes (’22 Ph.D.), who helped Chisum develop the GRIN lens system during their doctoral studies.

“Every pound of equipment carried by a soldier or hauled by a vehicle counts,” Chisum said. “Achieving the same high-speed connectivity with a fraction of the power eliminates the need to haul extra fuel and heavy generators, rendering entire tactical units lighter, quieter, and more agile, and mitigates serious logistical vulnerabilities.”

The project enabled Chisum to turn a physics breakthrough into a practical tool, clearing a hurdle faced by many academic researchers: the gap between laboratory prototyping and commercial manufacturability.

Chisum’s earliest lab prototypes, developed to verify the underlying physics of the GRIN lens technology, proved difficult to scale. One lens was created by drilling more than a million holes of different sizes across 100 distinct layers of material. The layers were then glued together over the course of 100 hours.

“The first prototype worked beautifully,” Chisum said. “But we couldn’t expect industry to consider such a laborious process for manufacturing without doing more legwork ourselves.”

Bridging that gap meant pursuing various advanced methods of 3D printing. The team began refining digital models of the lens antenna using computer-aided design software, replacing the drilled sheets with a continuous 3D-printed maze-like motif. With no straight lines or planar symmetry, the gyroid design yields a lens that is mostly hollow — and therefore lightweight — without sacrificing durability.

“Everything about the 3D printing process has to be precise in order for the lens to work at the frequencies needed for high-data rate 5G,” Chisum said. “From adjusting the geometries of the gyroids, to partnering with materials scientists to develop specialized resins, to pushing the limits of 3D hardware, we’ve made massive strides towards a viable, manufacturable solution for these antennas.”

The year-long project saw the development of fragile laboratory samples to rugged, field-ready units.

Strapped to the top of a Stryker vehicle — a cross between a truck and a tank — the antenna performed under real conditions. The vehicle navigated tactical courses, bumped over rugged terrain, and struck low-hanging branches. The GRIN lens endured, successfully maintaining a high-speed, continuous 5G data stream while drawing essentially zero power.

“Testing the antenna in the field was the icing on the cake of what was already a phenomenal opportunity,” Chisum said. “Proving that this tech works in the lab is one thing, but taking it out into the real world, knocking it around, and seeing it work? Here’s a system that can be used in a real network.”

With the viability of the 3D printing process and the ruggedness of the hardware proven, the GRIN lenses are entering a new phase of development. By overseeing technology and manufacturing, Cheshir Industries, which licensed Chisum's research with the assistance of Notre Dame’s IDEA Center, is working with the Army to ensure the antennas can withstand even more extreme operating conditions and be produced at-scale.

“The first question was ‘is it possible?’” Chisum reflected. “Once we saw it was possible, it became ‘can you build it?’ Now we’re in the phase of asking how to use it — how can it be integrated into existing systems? How does the antenna perform under extreme conditions?”

By answering these questions, Chisum hopes this technology will not only protect soldiers on the move, but will eventually pave the way for more sustainable, cost-effective 5G infrastructure in the civilian world.

“Our successful field test fulfilled a research objective while also setting the scene for continued innovation in the realm of antenna technology,” Chisum said. “We’ve taken an important step for advancing our nation’s wireless capabilities and surpassed a major milestone for the commercialization of wideband GRIN antenna systems.”

About Notre Dame Research
The University of Notre Dame is a leading global Catholic research university located in South Bend, Indiana (USA). Inspired by its Catholic mission and founder Rev. Edward Sorin, C.S.C.’s vision for the University to be “one of the most powerful means for doing good” in the world, Notre Dame’s faculty and students pursue globally significant research, scholarship, and creative endeavor that advances discovery, fosters innovation, and drives lasting positive impact. For more information, please visit NDR's website or NDR's LinkedIn. To learn more about the innovation unfolding at the University of Notre Dame, browse available intellectual property (https://nd.portals.in-part.com/).