Planar Feeding Techniques for Wearable Textile Antennas

Feeding techniques for textile antennas are of crucial importance to simultaneously address mechanical requirements of robustness while maintaining high RF performance. To assist in determining which planar feeding mechanism is best suited for textile antennas, a dedicated study of various planar feeding mechanisms is undertaken as one of the main aims of this article. Two of the most prominent techniques, namely the inset and proximity-coupled methods, are investigated on a quarter-wave patch, with particular attention to their suitability for various substrate thicknesses. It is shown that neither technique is suitable beyond a substrate thickness of $0.03\lambda _{0}$ . Consequently, a new textile feeding technique is proposed that blends aspects of the inset and proximity-coupled feeding techniques and represents the main contribution of this article. It is shown that this new feeding mechanism can serve as viable planar textile replacement for a coaxial probe feeding mechanism up to the substrate thicknesses of $0.05\lambda _{0}$ .