Textile Antennas, a Practical Approach

Within the framework of the development of a wearable communications system for a sportsman, a textile antenna has been realised. The required antenna needed to be low profile, washable, insensitive to the proximity of the human skin and relatively insensitive to deformation. To overcome the human operator coupling effects on the antenna input impedance, i.e. a shift in resonance frequency and an increase of return loss level, a practical approach has been chosen. This approach consists of designing an antenna in free space, well matched over a wide frequency band. Because of the requirements and design methodology, chosen was for a (log periodic) folded dipole array ((LP)FDA) antenna. Design equations for the antenna are discussed, measurement results of prototype antennas are shown and additional measures to tune the input impedance of the antenna are discussed.