Basements, tunnels, large buildings –– a weak Wi-Fi or mobile signal in these hard-to-reach places is frustrating. The usual solution is to add more electronics like routers, repeaters and base stations. Yet, as we move towards a 6G mobile network, this kind of complex infrastructure can be unsustainable and prohibitively expensive. Higher-frequency channels of 6G communications aim to provide vastly more data bandwidth than the current 5G, but those channels are more easily blocked by walls, people and other obstacles.
To tackle this, researchers at Aalto University have developed a new solution in the form of metacrystals: passive, 3D-printed smart panels that can shape wireless signals without electronics, a power supply or active tuning. The research will be published in Nature Communications on June 8.
‘When a room is too dark, you can bring in more lamps – or use simple mirrors to guide the already available light. This is what these metacrystals do, but with radio waves,’ explains doctoral researcher Mahdi Asgari. ‘Unlike previously proposed single-layer intelligent surfaces, these volumetric metacrystals can be designed to control multiple incoming signals or frequency bands independently — a key requirement for realistic wireless communication.’
The panels could be installed on walls, ceilings, furniture, or other surfaces to redirect signals around corners, into shadowed areas or toward specific users or devices.
Unlike many existing intelligent surfaces, which often perform only one task for one signal direction, the panels can handle several incoming waves at the same time, operate over different frequency bands simultaneously, work in reflection or transmission mode, and even fully absorb unwanted signals.
3D printed, custom elements
Conventional reconfigurable intelligent surfaces require many tuneable elements and complicated control circuits, which makes them expensive and difficult to deploy widely. However, the metacrystal panels can be fabricated using 3D printing, leaving the estimated price of consumable material at a few tens of euros per piece. This also allows for creating custom panels for specific environments, rather than having one universal device.
‘For industry, the most attractive use cases are static or slowly changing environments like factories, indoor 5G/6G networks, warehouses, and long corridors,’ says Asgari. ‘In such places, a passive panel designed for a known layout could be much cheaper and simpler than an actively controlled surface that requires continuous maintenance.’
Asgari says that complex electromagnetic functionality can now be realized as a low-cost, single-piece plastic structure ready to be put on a wall. These panels can quietly improve wireless connections in the background. Once installed, geometry does all the work.
Metacrystals could become part of everyday architecture
The researchers are now looking into pathways to commercialise the discovery and are seeking engagement from industrial collaborators interested in programmable metasurfaces, intelligent wireless infrastructure and low-cost passive signal-control technologies.
‘The hope would be that in the future we can see these scalable, smart wireless environments put to practical application in indoor spaces and outdoor urban settings’ says Asgari.
The next step is to move from static toward reconfigurable panels that can adapt when the wireless environment changes, he says. Today’s reconfigurable intelligent surfaces are often too costly and complex for broad industrial use, so the team is exploring simpler ways to fabricate tuneable panels while keeping them affordable and practical.
The paper, ‘Metacrystals: Inversely-designed 3D-printed intelligent panels for 6G communications’ was published in Nature Communications on June 8.