Soft and flexible UHF antennas for W-BAN applications

This work presents a novel technology for the fabrication of soft and flexible antennas that can be used for Wireless Body Area Networks (W-BAN). By using standard lab facilities we are proposing a technique on how to build robust antennas intended to work in a harsh environment. A silicon based elastomer Polydimethylsiloxane (PDMS) has been used as a substrate material while copper meshes are used as a conductive material. The initial fluid state of the PDMS allows several degrees of freedom during the fabrication process, both from the electric and mechanic point of view. The dielectric properties of the substrate are adjusted by loading the PDMS with inclusions having a permittivity lower/higher than the PDMS istelf. From the mechanic point of view, liquid PDMS allows the shaping of the antennas in custom prepared moulds, and provides a complete encapsulation of the conductive parts inside the substrate. Moreover, the final antenna prototype is completely sealed and encpasulated inside the PDMS. Several antenna prototypes have been built, measured and characterized. The built antennas are flexible and resistant to different external influences like dust, water or humidity. As a examples of environmental tests, the antennas were exposed to washing, bending and real body (environment) measurements.