Wearable antennas promise shirts with satellite link
By Jeff Salton
October 5, 2009
Gizmag has always had an interest in "smart clothing", whether it be a jacket that warms you on icy slopes, a coat that delivers an electric shock to ward off physical threats, vests that double as health monitors or even a concept bra that's supposed to help in the search for a husband. The latest research being conducted in the area involves flexible antennas which can be embedded in clothing, allowing the wearer to communicate with low-orbiting satellites wirelessly and exchange greater levels of information, including GPS positioning.
Joint research between Finnish defense and aerospace group Patria and the Finnish Centre for Wireless Communications at the University of Oulu is investigating the use of flexible antennas with the aim of demonstrating their feasibility in personal satellite communications, such as the Iridium satellites, which operate at low altitudes (Low Earth Orbit, LEO) - a development which could have far-reaching military applications.
A large part of the study has been dedicated to selecting a suitable substrate material that will conduct signals and be flexible enough to withstand the rigors of the wearer without sacrificing comfort. So far, several samples have shown encouraging results.
No easy task
Since the antenna is intended to be integrated into the clothing it needs to be self-conformal. This means that flexible wearable antennas should be able to adapt their form according to the body where the antenna is attached and still remain fully operational.
Researchers believe the study will determine which antennas perform best under stress conditions - as they are part of the clothing's fabric, they must be extremely flexible and be able to maintain communications as the wearer moves, and not be degraded over time by contact with human bodies.
Another major concern is how to make the antenna robust enough against manufacturing tolerances. Then there's the question of cleaning the clothing with embedded antennas.
Antenna material must also be light weight, inexpensive, low maintenance, need no set-up requirements, be robust and undetectable (for military applications).
The project has been on-going now for almost 18 months. So far, a survey of the state of the art textile antennas has been completed and several antenna samples have been chosen. Conclusions will be made at the end of this month to determine which materials are suited to wearable antennas.