Publication date

25 Feb 2026

WEARABLE ANTENNAS ON MOUNTAINTOPS

In an advance for innovative internet–of–things satellite connectivity, Stealthcase, a Finnish company successfully demonstrated connectivity with satellites in geostationary (GEO) orbit. This was achieved using a wearable textile antenna initially developed under the European Space Agency’s Advanced Research in Telecommunications Systems (ARTES) programme. The demonstration was conducted in real world conditions, with the fabric antenna maintaining a stable connection to satellites 35,000 km away. This experiment showcases the potential of new materials solutions as the adoption of non–terrestrial–network and internet–of–things expands.

The real–world test was held at Halti, a fell at the Norway–Finland border; two teams of hikers wearing jackets lined with Stealthcase’s textile antenna – produced in collaboration with the eponymous Halti clothing brand – tested the connectivity by exchanging messages as one group climbed, and the other stayed at lower altitudes. The fabric antenna, incorporated directly into the hiker’s jackets, maintained a strong signal connection with satellites in geostationary orbit, even in expected blind spots, such as the low–altitude area in the shadow of the mountain.

THE CHALLENGE: SIZE VS PERFORMANCE VS RUGGEDNESS

Antennas require a specific size relative to the wavelength they operate on to function optimally. Reducing their size to fit them on compact and handheld devices therefore incurs a trade–off in performance – and a commensurate increase in price. Concurrently, textile antennas thus far have been limited by existing manufacturing techniques and materials, restricting performance and making them ill–suited for daily use.

COMBINING INNOVATIONS

Stealthcase’s approach blends innovative laser processing techniques with groundbreaking antenna technology to overcome this challenge – bringing together ingenious manufacturing with ESA–supported research into antenna technology.

Leveraging the production techniques developed to process coated glass into energy–efficient windows that also let through signals, the Company was able to ablate conductive fabrics into a flexible fabric antenna. The antenna technology itself builds on prior work started under the ARTES programme to create an L–band satellite phone antenna capable of communicating with satellites in low Earth orbit (LEO).

“You can build something in a lab, write a paper and be done with your project. We want to build something that works, something that lasts,”

Juha Lilja, CTO at Stealthcase

BUILDING A RUGGED PRODUCT

The novel production method allowed Stealthcase to overcome a significant obstacle to the usability of textile antennas – weathering real life wear and tear. Fragile coaxial soldering and conductive adhesives having proved unreliable, the Company patented an impact–tolerant RF interface, integrating circuit boards directly with conductive fabrics. This elegant solution enables a new approach to the traditional trade–off for antennas: by building them directly into the fabric with no wires or snappable parts, the antennas can grow as big as the surface of the object they are sown into.

REAL–WORLD PERFORMACE

Stealthcase’s technology merges RF circuitry with conductive fabrics, enabling customisation to different frequency bands – from VHF up to GHz frequencies. By turning the entire fabric’s surface area into an antenna, the Company is able to

adapt the LEO antenna technology developed with ESA for GEO communications, maximising both power and range to operate on S–band.

During tests, the wearable fabric antenna performed as well as – and sometimes better – than smartphone antennas. The textile satellite transceiver achieved low variation, low loss signal, with as much as ten times less interference than phones. Its Specific Absorption Rate (SAR) was measured by Radientum at 0.15 Watt per kilogram at 868 Mega Hertz ISM bandwidth 20 decibel-milliwatts continuous wave transmission power with 10 grams tissue averaging.

In real conditions, the performance speaks for itself: The fully integrated wearable satellite messenger in the Halti jacket provided two–way connectivity through a GEO satellite link.

MADE–TO–ORDER CONNECTIVITY

Stealthcase’s manufacturing process makes this innovative satellite communication solution highly customisable and affordable. By adapting its laser–based processes, the Company can produce textile antennas and soft, conformal components in a scalable and repeatable manner.

The immediate applications for embedded satellite communications can help improve safety for emergency services, first responders and remote workers by replacing bulky equipment with seamless, accessible connectivity where no terrestrial network exists. This solution also meets with emergent trends in IoT applications, making its resilient, customisable design an enabler of innovation for future applications.

“Turning clothes, life rafts, and more into antennas makes sure we can keep people connected when they need it the most,” said Hoda Nematollahi, Antenna Engineer at ESA. “Stealthcase’s work is a great example of the unexpected solutions and innovations that come out of ESA-supported research to enable new businesses and applications.”